What to do when a taxi driver uses the meter but at the end of the ride clears the meter and pretends we had agreed on some higher price for the ride?

Had something similar happen going from Tunis airport to central Tunis. The driver (who had a "mate" with him, so I was skeptical from the outset) had the meter on, but just before the destination he turned it off (at which point it had reached 5 dinars). I only had a 20 note to spare and he wanted to give zero change. He eventually gave 3 dinars back (LOL!) whereby I fetched the phone and said calmly and smiling (in French) "we don't need the police here, do we?" whereby he sighed and gave me another 10. Still 2 more due, but I left it at that and got out, finishing by sternly saying "no fraud, I don't like that!"

Another time (admittedly off-topic) I was in Belgrade and had an early-morning flight from Skopje, but the last evening bus Belgrade-Skopje was cancelled, so I got a bus to Vranje where I arrived around midnight. A uniformed police officer I met on the bus helped me get a ride with a "Happy Taxi" driver he knew, whereby we settled on 50 euros (a fair offer). However, as he was re-fuelling near the border, he started complaining about how expensive the tolls and fuel were and that I'd have to pay for it. I gave a weak reaction, to make it appear I didn't really understand what he said, in order to make it to the airport hassle-free. Once there, I gave a 50 note, and when he asked for another 60 (!) I politely said (in Serbian) "In Vranje you said 50, and I know that's a normal price, so here you have 50. Have a good night" and went away.

Both times I had no luggage in the back, which does make matters easier.

Remain calm and say you have left your wallet in the other bag, which is in the trunk. He will of course know that's a lie, but he will also realize nobody will proceed until the baggage is offloaded first. Prepare to wait several minutes if he is really stubborn.

Eventually the taxi will attract the attention of security personnel or his colleagues by holding up the line of taxis

In situations like this I never pay, I simply leave, if they want trouble ok lets get the police involved, in most countries, the driver has a lot more to loose than a tourist who brings money into the country to spend.

Moreover many countries do not want a bad reputation either with this type of things.

But be VERY careful if you are not a seasoned traveler and know what countries this does NOT work in then better pay the metered price and leave.

You're asking how to win an argument when being fleeced. You can't. All you can do is hope it doesn't turn into a robbery. No thinking person would ever honestly believe that you agreed on a higher fixed price... The problem is that in countries like these the police either don't care or are part of the racket. Even if they do care they won't come in time to save you in the moment.

What to do? Saying "no" and getting out of the car is a great start (although he might have your luggage in the trunk). If things get violent either give him what he wants or defend yourself. Compliance is usually safer, I've never been to Thailand but I'd pay almost any sum of money not to be interrogated by their police for fighting a local who may or may not have organized crime connections with them.

Talking is still your best bet overall. These kind of things can often be preempted by making polite smalltalk and making yourself less of a mark by showing you know a bit about the culture. Very few of these people are ready to commit a violent robbery so if they still change the price just be firm but polite. No negotiation from the metered price, but also no insults or ego challenges. This is not a misunderstanding but you can still deescalate.

Also understand that a lot of cultures are far less direct and formal than their American/European counterparts. When originally writing my answer I didn't realize that 45 THB is $1.35USD. If you're an American he's asking you for pocket change because he's extremely poor. If this were a proper shakedown he knows you have tens to hundreds of times that amount on your person.

In many places taxi drivers are quite busy, so they try to avoid losing time with you because that costs them money they don't get from the next client.

With this in mind, keep insisting on a sum you think is fair, and refuse to pay more. Unless you're late yourself, there's a high chance that the driver will be the first to give up the game.

Things get much more complicated if you need to get a change from the driver. You can still keep sitting in the car waiting for the change, but psychologically it's easier for the driver to agree to get less than to part with the money they already have in their hands.

In my experience, Thai taxi drivers can add extra costs based on distance (extra fees for short distance) and where you're hailing them (50THB extra for hailing from an airport).

Similarly, if you hail them from specific spots, you may be given a slip of paper containing information of driver and other relevant information like this:

While noting that you won't be given one of these for every ride, if you do get handed one of these, I'd recommend contacting the numbers on these papers first, in the case of the image above, that'd be the airport, and then the ministry of transport.

The simple answer is Immediately phone the police.

Just sit there quietly, say and do nothing whatsoever to the driver, and begin phoning the police.

If necessary just phone or text your friend or whatever overseas, and ask them to look up for you how to dial the police locally.

Best way is to workout all the time, it'll keep you fit and intimidating so this kind of stuff is less likely to happen to you.

Second best way is to joke it off with the driver, say you don't have cash, you can't understand, talk in klingon, tell him a boring story about your childhood, act like a 5 year old, bullshit with the driver, it's fair game because he's bullshitting with you.

If that fails, cause a scene, get angry, cry, open the window and pretend to call for help, call the police (or pretend to call the police even if you can't), and then bullshit some more, he'll be more agreeable if you're not worth the trouble. Don't start a real fight, that will not end well most of the time in a foreign country.

If possible, say yes to whatever, insist on paying once he gets you to your destination. Once there, make sure you have your luggage. Then get out of the car and negotiate outside, or just pretend you haven't met the driver at all.

If you can't get to the luggage, just sit there but don't pay. Wast time, open the door so he can't drive around, but sit until you can come to an agreement. Someone has to give up once the time wasting isn't worth while anymore.

If all else fails, just pay him.... if your bad behavior is not enough to get you off then it's not worth it getting your head bashed in over a few bucks.