I too have heard this process was free, but was charged 500 baht at Udon Thani immigration.
With a 30 day extension, I was in and out in 15 minutes and they made copies for me as well. My first extension not involving 2 hours at Samui immigration so I didn’t fuss much merely for the convenience.
because one bored receptionist probably won’t give the same information that a group containing thousands of expats with experience in such a matter might know.
If you hate the pursuit of providing/receiving information why are you here?
How about YOU give them a call and then provide a worthwhile answer to this gentleman’s question? Too much work? Than maybe you should not reply.