Question: what documentation is required from my Thai bank re: $800k THB I deposited for retirement extension?

I’m U.S. citizen, over 50, entered Thailand as a 45-day visa exempt tourist, expiring Nov. 20. $800k was deposited on August 30. I’m located in Bangkok. (So non-immigrant O, TM87, I believe?)

I went to Bangkok Bank today, they had no idea what I was talking about, but gave me 3 documents: a letter stating my balance as of today, a printout of the $800k transferred in, showing it came from outside of Thailand, & a copy of my statement for the month that the transfer came in, showing the funds transfer. Is that sufficient for immigration? Thanks for any advice!