I have had this one day biz about 3 or 4 times. Never had to pay. They just puta comment under the stamp in my passport. I once was going to Penang by train and I was 2 days late and I had to pay the 1000 baht. It was rather funny, at the same time there was a group of English girls, who had forgotten the date and were almost a week over. They were all rather gorgeous, laughing etc. The Imm boys took it all in fun too and just made them pay the amount due i.e.the train was held up because of all this.