@Steve ******
surely if they want extension and go to immigration and they have not had a TM30 filed, they are likely to get fined for that on top of the 1900 for extension? I went to Prachin and they asked for mine, had to drive back to get inlaw's written permission to do TM30 on their behalf, also had to go to police station for a replacement tm6 exit card (at least that was free a I did not have 2 baht on me only 1000 lol) all of this for 2 days extension i needed, same as OP.