Lloyd Turner. You should know by now when people make an error, they blame it on the device they're using! Like those who can't spell "border"! 😃

Extensions can only be carried out at an immigration office.

Which visa are you on?

You can fly from U-Tapao Airport to Chiang Rai. It's the closest operational domestic airport to Bangkok

David Broadfoot. You have to completely separate the two extensions and ensure you meet (or have met) the requirements for both, but if you are switching to monthly from annual, you need keep only 400k in the bank up until your application date, provided you have the full 12 months of monthly deposits for the new application. So, in theory you have met the two months before/three months after 800k, and 400k for the rest of the year requirement for extension 1, and you will meet the 12x65k requirements for extension 2. As soon as the year is up from extension 1, you can withdraw the 400k and go out and get smashed (except there's no bars open).

Donald Crawford. Keep in mind also that is 12 calendar months requirement, not 12x for the year. So if you make two 65k deposits in January, and then skip February, you'll be deemed as not meeting the monthly criteria. It's anal, but it's what it is

Nigel Phipps. I walk five minutes to my post office, five minutes inside, and five minutes back home.

You don't have to go to immigration. You can file online or if in Bangkok send it by mail

Have you tracked your letter to see when it arrived at CW? You may have left it too late to submit postal lodgement, as the website stipulates 15 days before

John-Paul Riva. Yes. Thailand Post Office. 70 baht