Thank you for your interesting post. I have never had a visit for retirement, only for marriage. But I correct you: You did not apply for a retirement visa renewal. You applied for an extension of stay based on being over 50 years of age.
You are in a catch 22 situation. To get a Retirement visa, you need yo season money in a Thai bank account. But you cammot open a Thai bank account on a tourist visa. You need to get a long term visa before coming to Thailand. Then you can open a bank account and get a retirement visa.
Yes if you have a NON-O visa you certainly can open a bank account. But until you get that visa, opening a Thai banl account will be impossible. And you need to season your money in a bank account to be able to get your NON-O visa. Catch 22. Your plan will not work. I suggest that you get a long term visa before you come to Thailand. With this, you cam then open a bamk account.
If you get the 60 day visa exempt stamp and extend by a further 30 days at the Immigration office, Immigration class you as a tourist. If you then attempt to enter again on a visa exempt stamp, Immigration rightly consider that after on 90 day stay in the country that you are no longer a tourist but that you are attempting to live long term in the country. While there is no legal limit to the number of Visa exempt entries, once the Immigration officer believes that you are no longer visiting the country as a tourist he will deny you entry. If you have already stayed for 90 days on a visa exempt entry, then in future to guarantee entry into Thailand, you need to obtain a long term visa suitable to the reason for your stay.
Out of interest: Thailand has recently cracked down on foreign nationals abusing visa-free entry. Between January and May 2025, immigration officers denied entry to approximately 8,193 foreigners, many suspected of entering under the guise of tourism to work illegally.
You should not have any problem. Every bank is different. Every branch is different. Even inthe same bank, staff will give you different answers. Even a letter from you hotel stating that you stay there might be enough without needing a certificate of residence. You may need to try a number of banks/branches.
The proceedure is: 1. Get a Retirement Visa prior to arriving in Thailand. 2. When ther Retirement Visa is close to expiring, you then apply for an Extension of Staay based on being over 50 from the Immigration Office inside of Thailand.