you can definitely get an agent to help you in person. It's a really easy process though, and I don't speak a word of Thai either (I'm trying 😅). I just have my phone out with Google translate a lot, but it was really easy to do in Chiang Mai.
AuthenticPassionfruit644 can you provide details of the agent? I know people that could use the help, but all the agents they have contacted have said they can't do the licence conversions as it must be done in person.
You need a doctor's certificate, residency certificate, your IDP, your home countries licence and a passport photo. You need to go in, an agent can't do this one for you. You need to do an easy reaction time test. Make a booking online so you don't have to wait around all day.
I'm commenting from an Australian POV, from a similar situation. I had my money in a high interest savings account with my regular bank. Accessible instantly as you have said as well. Mine was accepted no problem at all