@Jay ******
When I was a Thai newbie a friend put me in touch with Siam Legal, who, for a fee accompanied me to CW immigration to get the initial 90 non imm O, (I was on a TR60 back then) and about 3 months later they call you up and take you back to immigration.
The lady who dealt with me did all the negotiating with the IO on both occasions. I sat in the waiting area and watched.
I realised that it was not difficult to do and have done myself since then.
This was a very long time ago, so I do not know if they still do this or how much it would cost. But, at the end of the day I had a 100% legal retirement visa