Thanks for sharing. My husband and I are living in Nonthaburi, too. We’re both from the US, though. We already got our first extension stamp at the Nonthaburi office which is valid until the 16th. We’re going to have to take our embassy letters there for Covid-19 extensions soon. It looks like we should print some extra things out just in case... I really appreciate you sharing your experience!
I would do a search in this group. A lot of people have already posted about their experiences and your country is probably covered. The general knowledge is that you need to get a letter of support from your embassy (a lot of embassies are doing them by email. I’m from the US and they are just handing them out to anyone who asks). You take the letter to immigration and they’ll sort it out. But, definitely look through the other posts and comments. Lots of this information has already been shared.