So Krabi immigration is corrupt, good to know. That's why the Pai immigration office was banned from doing extensions last year because they were charging people 3k baht for them.
Just where you're staying at the time, and realistically as long as you have one in the same province as the immigration office you're apply at it doesn't matter. You could have a Tm30 from 5 years ago, as long as it's included with your application that's all they care about.
A Tm30 is required anytime a foreigner sleeps at an accomodation (law says 24 hours). Hotels, guest houses, family and friends are all supposed to submit one when a foreigner stays at their address. In practice hotels are the main ones who submit them though.
When you go to immigration for an extension, they need to see proof (a recipt or screen shot of an online submission) that a tm30 has been filed for you, meaning your address has been filed with immigration. If you're staying at a hotel, just ask them for a screenshot or print out.
Oh trust me Mick, I'm important. My local 7-11 knows me by name. And I was referring to your embarrassment of a comment "sHe a GueSt In tHe KinGdoM!"
No, she's a customer in a business transaction that was poorly planned, explained, and executed by the merchant. If the merchant can't be bothered to care about her covid test, than neither should she.