Thanks to everyone for the information given. I arrived at the immigration office about 10am and there was a queue of about 20 in front of me for 90 day reports. When it was my turn I informed the one and only staff member that it was my first report at Jomtien. She checked that I'd submitted at TM30 already, then gave me a queue number with waiting time of about 40 minutes. 35 minutes later collected my passport with a new reporting date in March. No forms or copies of anything were asked for.
What I found disturbing was the fact that several foreigners were having stand up arguments with this unfortunate member of staff who was doing her best to deal with dozens of people on her own. It's seemed to me that some of the arguments were from foreigners who think they know better than than the immigration staff.