I went today to Chiangmai immigration offices to extend my Non Imm OA visa ( from UK) re entry permit.
I asked for 60 days due to COVID. I got a under consideration stamp told to come back in 15 days when they said would give me another 45 days.
It took a few hours some form filling in and photocopies cost 1900 baht they did ask to see my insurance which I have.
The volunteers at immigration were really very good it was my first visit. I was impressed with the process,and Thai staff.
Just posting as I have had help from this group and thought may assist.