old news I did that last year and my IO was quite content with it. I have done everything by the book but they still freeze my account. As I am in the UK there is nothing I can do about it until I get back. Any bank that prevents access to my money with no notice at all is NOT one I will continue to do business with. Both my other Thai accounts are functioning as normal. I'm done.
My monthly payment was deposited from uk into my BB this morning 23 hours after initiating transfer as usual. I am unable to check how it is coded as I have been denied access to my banking app. Can't do anything about that until I get back to Thailand next month.
I didn't need a letter. Just 12 months statements I printed myself from the app together with bank book both of which showed transfers. Also bank statements from the bank the transfers were made from.