There's no official limit. Purely at the discretion of the immigration officer when you enter. Expect to be denied on your third attempt. As soon as they work out you're abusing the visa exempt concession, you're done, with a black mark on your immigration record. There's a reason Thailand has a variety of visas allowing longer stays
Bangkok Bank overseas are only for corporate customers, not for retail banking. You're correct. HSBC pulled out of retail banking in Thailand some years ago, and their presence now is strictly corporate
That's because you don't have to be there in person. Someone else can do it for you. Agents do it. Bumrungrad Hospital can do it for you for 500 baht. I do it by mail every time. What you showed me was a generic rejection slip which can be sent from any immigration office. I will repeat (once again):- Bangkok Immigration Office accepts postal 90-day reports for ANY report. I have zero knowledge of other immigration offices
Yeah but not in Bangkok. And you have to apply 15 days before the due date. I've used the mail method for years, whether it's first report or not. I just did one a few weeks ago. It works, but not every office allows it