My friend has been staying in Thailand on SETV's with 30 day extensions. He has been getting his extensions at Nakhon Si Thammarat immigration office but was told after his fourth extension that they would not give him any more extensions. They didn't put any prohibitive stamps in his passport - it was just a verbal warning. He had no problem getting his fifth SETV from Vientiane last week (3 from Penang, 2 now from Vientiane), but he is not sure where to get his next extension from. I have heard about consecutive visa applications being blocked at certain consulates on the grounds that the applicant is 'living in Thailand on a visa not designed for that purpose', but haven't come across any reports of extensions on issued TV's being blocked at immigration centres within Thailand for this reason. Is this happening in other immigration centres or is it just a one off? Any suggestions where he should go to get his extension?

It is a one off occurrence by a less than friendly immigration office.

He could go to another office if he could put a local address on the application form. A one night stay someplace would work.