You also might still be required to have health insurance cover for approx 2.5 million bht. But please do check as so much has changed since i converted my OA to a non o retirement (which does not require insurance, but you do have to have your eight hundred thou in a Thai bank account.
In Phuket, you can choose any bank that will have you. (Bangkok bank didn't want to know). Im with Krungsri, who were more than helpful, spoke excellent english, and produced statements and letter and updated bank book all in a short wait when needed😉