Granted admission on WB instead of B1/B2, Denied Correction by CBP

Hoping someone can help me here, Just trying to find out what options I have.

I first travelled to America on a WB in Aug 2018 and left in Nov 2018. While back in Australia (my home country) I applied for a B1/B2 visa which I was granted as my work required me to stay longer for training and to attend a trade show for my next visit! I then re-entered America in Jan 2019, however was granted admission under my previous WB (Visa Waiver) instead of my new B1/B2 visa, as I had been booked for training and trade shows for a full 6 months I attended the local CBP Deferred Inspections site to request they change the status from WB to B1/B2 which I was denied- My problem is now I am required to finish my training of an affiliate companies clients as well as attend the trade shows as planned but am required to now exit the country by Apr 2019!

Am I able to go to Canada or Mexico for a week and then re-enter on my B1/B2 before Apr 2019 instead of the WB thus extending my time?

Or will I have to fly home and then try my luck flying back into America to re-enter on a B1/B2 that way,

Either way I’m aware there’s a good chance I could be refused.

Any options would help me greatly as I’m getting quite a lot of stress from my work in Australia and the requirements I have to complete in America.

Thank you in advance.