Its a Wise limit. Use XE and the limit is much higher but I'm not sure what. Not much more costly than Wise. Failing that get a Bangkok Bank account and limitsxare higher and more likely to show as ftt uf that is an issue for you.
Apply for 90 day non o in the UK before you leave using banked money in home bank account for proof of funds. Come to Thailand and open a bank account and deposit
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0 baht at least 2 months before your 90 days runs out. Once the money has been banked for two months you can apply for 12 month extension based on retirement being over 50. You will find it easier to open a bank account with non o visa than you would if you entered visa exempt or with 60 day tourist visa. Even with 60 day tv you only get one extension giving you the same 90 days.