Airline and Travel Agent disagree on baggage allowance, who do I need to resolve it with?

If you buy a mobile phone, and the store tells you it has 2gb RAM, then when you reach home and open the box, you find that it has only 1gb of RAM (and the manual states the same as well), who's to blame now? the manufacturer or the store? of course the store.

The same exact thing happened to you. Regardless of the reason, whether it is plain cheating, misunderstanding or whatever. Your opponent is indeed the travel agency. The airlines responsibility starts when you check in.

What to do

1. Email them again, this time attach the screenshots, the ones you had when you made the reservation and a screenshot from the airline's website where it says "only hand bag", make them understand.
2. Call them, talk to a human, these things are better explained with voice calls because they can't skip lines as they do when they read emails, so no cut&pate replies without understanding that it is their mistake.
3. If nothing from the above works, go public! and that is twitter, attach some screenshots and hopefully this will solve it, reputation issues will make them pay attention.

It's the Travel Agent's responsibility. Period.

A Travel-Agent that transfer you to the airline to solve your problems is like your lawyer telling you to go convince the judge you're innocent. It's their job.

Let me explain why: Travel Agent are the middle man in this scenario, they work for the airline to get you a seat. Once they do that, they either take commission from the airline or/and take service-fee from you (the passenger). The 'buy' transaction is not where it's all over. They are now working for you because you paid them. They're providing you a service by answering your questions, providing alternatives if things get wrong and so forth. It looks like you have sufficient evidence to support your case -simply email them with the screenshots you have and ask them to followup.

A friend recently had this happen. He'd booked a flight for his family (moving from the UK to Australia) with Emirates, through a travel agency. The flight had a special code with the agency, meaning they could take extra luggage.

At the airport, they were told they were over the limit, the code wasn't on their booking and they'd need to pay an extra 2000 pounds(!). Despite a crying kid, very upset people and it being fairly obvious there'd been a lack of communication between the travel agency and the airline, neither was taking responsibility.

He ended up having to pay, or not get on the flight. It went on for months afterwards before it was shown that while the agency had booked it, either they'd not used the code or the airline hadn't received it. Moral of the story - check with the airline as well as the agency to make sure the allowance will be recognised, because it's up to the airline's gate staff to decide if you're getting on the plane at the end of the day - they won't care who your travel agency is.

If you can't confirm, or there's a discrepancy, get it in writing from your agency that the allowance is what they claim it is. That way they'll be responsible if it's not accurate - after all, they're the ones who sold you the ticket, not the airline. To take it to an extreme example, if the travel agency promised you free pet baby llamas on board, the airline clearly won't be providing that and it'd be the agency / OTA at fault. They're the ones specifying what they're selling, you and the onus is on them to be accurate.

A tip I've found, if you're really getting nowhere, is if the OTA has a twitter account (or perhaps the airline as well) send out a public tweet about it (polite but accurate) about their failings, and it's surprising how quickly you'll often get a response, and they'll try to sort it out. Bad press is something they tend to want to avoid.

Given the details you provide, this answer is not going to be specific for travelling. To me, the crucial part of your case description is this:

The OTA seems mostly to respond in cut'n'paste standard answers, so haven't yet replied specifically about my screenshot, not specifically about their website disagreeing with the airline.

This seems to be the typical procedure of "customer service" with a large number of companies (phone companies, online stores, etc., all alike). It's a tactic of answering with unrelated or nonsensical responses that don't help you with your problem, but are only meant to annoy you, hoping that you'll eventually give up. In my experience, the most effective strategy in such cases is to collect evidence for a reasonable amount of time and then contact where you can realistically expect someone human to get your message:

• Continue the dialogue with "customer service" for a few mails. If your time till the travel date is sufficient, do try to reach a "ridiculous" level, such as 20 mails, there.
• Do not overthink what they might be thinking, or what they already know. Such "customer services" tend to keep the complete conversation history of the support item as a fullquote in all mails, yet are usually totally oblivious of what was said before.
• Write clear and simple questions. For each question not yet answered, ask explicitly why that question was not responded to.
• When you receive a response that points to something that was already ruled out in a previous mail, explicitly point out that you already told them XYZ is not possible/applicable.
• Write all of these e-mails in a calm and neutral, possibly friendly, tone. If there are any people on the other side, they should be annoyed by the repetitiveness and (in your case) uselessness of their work, not by your behaviour. (If anything, that might lead to someone actually making an effort to truly help you, at which point you can abort the process described here.)
• Under no circumstances, call them by phone. No matter how often they insist that you'd get "better service" by phone, that's just another copy-and-paste text of theirs, and it's their attempt to get the conversation off the (yours, at least) record. The result will just be that you have no written transcript of what was discussed, and if things become serious, the company will claim "customer service" told you information XYZ on the phone.
• If you like, you can also send a paper letter to "customer service", citing your previous conversation, and see what will be reponded then, to obtain some more tangible evidence.

That concludes your contact with so-called "customer service".

• Once you have collected a notable number of e-mails during your exchange, write a paper letter. Do not send it to customer support, send it directly to management. If such a service is available in your place, send it in a way that receipt has to be acknowledged by the recipient with a signature card that is sent back to you.
• In that paper letter, write clear, single, questions, both about your issue and about the incompetence of "customer service". Point out explicitly those conversation passages where "customer service" sent back nonsensical instructions, whose preconditions were already ruled out in previous mails.
• Attach a full transcript of your messages with "customer service".
• In your text, do not hesitate to emphasize how disappointed you are with the company's performance, and how you cannot recommend it to anyone who asks you for advice any more.
• Set a firm deadline for the company to react, for example, two or three weeks. Explicitly state that, no matter what, you will consider the option to press criminal charges for fraud (and that's a good place to cite/point to the explicit statement about luggage fees from the company's website again). (Of course, write that in a way that is realistic in your place.)

That should work to solve your immediate issue, and if you're lucky, you might even get a "We're genuinely sorry"-freebie from them.

There's the question who is right, and there's the question how you get on your flight with both one piece of checked-in luggage and your hand luggage. The second question might be more important to you, and your only choice may be to pay the airline. If you ask them they will most likely at least send you written documentation that the travel agent booked a flight without checked-in luggage and that they got paid for a flight without checked-in luggage, so when you fight it out with the travel agency you have evidence that it was the travel agency's fault.