Make sure you have the passport your DTV was applied for with you and make sure they stamp it 180 days! My passport expired..
Ok, so I'm used to visas being printed and stuck into my passport - old school maybe..
Anyhow, came here twice on my DTV, gave them my new passport, all the DTAC and DTV paperwork at immigration. Smiled, heard him stamp my passport, off I went.
Only to glance at my passport 50 days into a 70 day stay and noticed the last two VISA stamps were 60 day tourist visas. Went to a visa place. They charged me 4k bht and said all sorted.
Got to the new electronic passport control, red warming lights and off to immigration..
Long story short:
1) Visa firm had done nothing, no notes on record
2) Showed him my paperwork, correct DTAC with visa number entered on both occasions. And valid DTV
3) He asked to see my last passport, showed him a pic. All good.
He then advised me to bring both passports as the DTV visa is assigned to the old passport. (I can get that changed at the embassy apparently when I'm back)..
Told me to make sure they stamp it correctly...
Then stamped my passport and said "all done, have a nice day".
Bit stressful but easy enough to be fair. He said having all the paper visas helped a lot. So much for the visa company. Will be paying them a visit in four weeks wjwn I'm back.