Was it the exact same ID used to open both? (eg, not 2 different passports, even if the name is exactly the same?) That COULD be the issue. Otherwise, after the 5 days are finished, and if you haven't has a result, chase up with your specific branch again. This is just the banks performing KYC. This has, and will keep happening with different banks globally. And definitely more scrutiny if you are not a citizen.
As for paying rent, you should be able to send a wire from your UK bank to your landlord's account. Not sure bout anything else. I would expect there to be a way, until you sort this out.
Elite/privilege visa, if you have the cash. Otherwise, you will need to get a marriage or retirement visa with the 90 day check-ins. No need to leave the country.
, having a home base is nothing abnormal. I would bet more than half the countries in the world would have the same requirement. You can move around, just register the move appropriately.
asked, have you actually been to Thailand, and know where you plan to stay?
Are you remote working for yourself? Or remote working for a company? The requirements are different for each. And if you plan to work as a teacher, that cannot be done on the DTV.
Will your oldest still be 17 when you come? I think they would be considered adult at 18 (Can someone confirm this??). The requirements might be different for them.