Separate 100 thb to each plastic bag and then go to 7-11, I've done this several times. If they refuse, just tell that you need to deposit the money into your bank account, the charge will be only 15 thb.
You can provide them the application form frist and after they approve you can make a payment, Krungthai Axa also can do this way. It's takes some time because there are many processes, especially if you are from sanction country naka.