I opened my account in Hua Hin, then a year later moved to Sriracha and the Bangkok bank there issued the statement and letter within about 10 minutes for me, so it's definitely possible. I have heard anecdotally that not all banks are as cooperative (I don't know if this is true).
I agree, but you can avoid the fees by using the cardless withdrawal option on the banking app instead of using the bank card (I never use my bank card).
you get the non o visa from the Thai Embassy in your own country using your currentbank statements. Then travel to Thailand, the non o gives you 3 months, so you can open a bank account in Thailand and deposit the 800,000 baht ready for you 12 month extension.
no, you can use your UK bank statements to prove you have sufficient funds to apply for the non O in the UK. Then when you enter Thailand with the non O visa you are able to open a bank account because you have a long term visa already. That's why I said it's the easy way to do it. If you open a bank account as soon as you arrive and deposit the 800,000 baht, it's then easy to apply for the 12 month extension of stay, once the money has been in your Thai account for 2 months.
Easy - get a non-O retirement visa online from the Thai Embassy before coming to Thailand.
Difficult - Travel to Thailand without the non-O and hope a visa agent can sort it for you.
It used to be quite easy to come to Thailand without a visa and apply inside Thailand, but the banks will not open a bank account for you now, so it makes it very difficult.
retirement visa is much easier. Many people that are married to Thai women (like me) get the retirement visa to avoid the difficulties. Go to your local immigration office to get their list of requirements as every office has different requirements. If it's the 800,000 baht that's making you choose the spouse visa, you can switch to the monthly 65,000 baht method at the second extension and withdraw the 800,000.
I think I read that Bangkok insist on 90 day report first, but other immigration offices (like Hua Hin) don't require the 90 day report, so you might be better stating which office you use.
This situation seems to be happening a lot since the recent crackdown, it must be really annoying for them. Have they asked what they need to provide to open an account? They might need an agent to help or maybe travel Surat Thani to see if they are more accommodating there?