On the 26th apply for extension in which they will refuse & issue you 7 days to leave country. This will cost 1900, but gives you amnesty till 3rd oct. you then have to pay 3500 upon leaving country for overstay of 7 days. If you do nothing now, then will cost you 7000 for 14 days overstay. You will save 1600 by applying for extension on the 26th!
I got a letter from the British embassy 3 days ago requesting 30 day extension whilst waiting for my non-Imm visa. I made TM7 application on Wednesday. Paid 1900 & got stamp to return in 20 days.
Medicine back home is free & very expensive in Thailand, so I brought 6 months supply with me. I carry a doctors letter &’prescription only to show at the check in desk at departures. I’ve never had to show the letter when arriving in Thailand & no questions ever asked. Two of my friends have also took 6 months supply with them together with a copy of my prescription. Again, no problems.