@Michael *******
I’ll be honest with you. This post doesn’t sound correct at all. There *may have * been a misunderstanding about the requirements. I have joined the Phuket expat groups and the islanders groups. You’re first person with this problem.
My advice: if you meet the seasoning requirements of 800K THB seasoned in a bank for two months before you apply, three months after you apply, and not let the balance fall below 400K during the in-between, they should give you the extension of stay