With some Banks such as Bangkok Bank the 800K needs to be in for 4 months prior to applying, also most banks will not give you the required paperwork for immigration if you only have a tourist 'visa exempt'
If you opened your BB account on a tourist visa it would be a good idea to go in and verify it again as they are blocking all accounts with short term visas, you can only open one now with a long term visa such as retirement, as mentioned above you can always open an account with another bank and move the funds over.
It's disgusting the way they are doing this to their clients and many times without notification, the only way they find out is when they try to pay for something or withdraw some funds, I for one will be closing my Bangkok bank account when all this is sorted.