I submitted an online report at the newest webpage version. After 9 days at status pending I went to do it in person at Samut Prakan IO. This was on the 15th, the report was due on 12th. So after getting an approved report at 10:30am at the IO, at about 16:00 I had a reject response from the online system.
My app still incorrectly shows overstay, which I believe it pretty normal as TM do not update their database. Better luck next time I hope.
I should have waited until nearer the old extension due date. This is why I mentioned the possibility to renew 45 days earlier, which is fine if you don't change the reason.
Would the advice have been to renew on the next extension due date?
I did express my surprise and ask if they were cheating me, all with a laugh and smile... hopefully next time I will be using an immigration office in another province 🤣
FYI Samut Prakan immigration charged me 500 THB for the certificate. They asked me whether it was for car or bike, and I naively said both. Total fee 1000 THB from immigration as they needed to give me 2 certificates! Cheaper than a uk embassy letter though.
The Land Transport office were quite happy with a single letter plus a copy, so I have a spare original to remind me how effectively government offices work. This was for a renewal btw last November.