i think that is a good method, I do something similar with a Starling bank card and use it to pay for things anywhere that will accept a card. I am retired here, so I need a Thai bank account to deposit money (for the visa) and use that for cash.
you were told incorrectly. There's a lot of wrong information given by people. I used Wise for my bank transfers to Bkk bank and my non o retirement visa and subsequent yearly extensions were approved with no problems.
If you use Wise don't forget to use the correct reason, which is something like "long term stay in Thailand" (someone will correct me with the correct wording), it was the last one on the list when I used it a while ago.
I don't know if it has changed in the 2 years since I did mine, but the site is very "clunky". The questions are badly worded and the format to upload documents was unclear. I managed it with a lot of perseverance and provided the same evidence several times. I remember a question about the ID of the person that invited me? I invited me, so I used my passport page again and it was approved, so don't be scared of attaching the same information several times.
The problem with your request is that a visa agent in Thailand cannot help you with it. If changing file formats is what you need help with, I would ask a friend or relative that is more computer literate to help instead of risking sharing your information with a stranger and wasting money.
I bought my car the way Stuart suggested. I had to increase the daily limit to cover the amount, but it worked with Bkk bank. Failing that, I think you can go into your bank and get some sort of payment mandate to cover the exact amount (apologies I don't know what it's called, it seems such an old fashioned method), but the bank will charge you for the service.