The Best thing to do is actually talk to the immigration office Your will be dealing with.They can provide a letter to open a bank account. Based. on a non o retirement permit some people who have used an agent to try and get around this have had their bank accounts frozen, just be careful.
Wise has reduced its fee recently i used them straight in to my Bangkok Bank account ,always tick funds for staying in Thailand it shows as an international transfer. why don't you just do the Visa yourself rather than the use an agent getting the bank account now is the hardest thing to sort out.