Phuket-Hua Hin style scam
Adjarn,
A girl I was with, I picked her up in Patong and took her to my room in PhuketTown, had to call someone. This was before the days of cellphones, so we went outside and, guess what, uncle was ill and she needed to go to Buriram immediately (in the middle of the night...)
I told her she could go anytime, but I would only pay in the morning after I cashed a check. It was before the days of ATMs as well.
She stayed and never talked about uncle again. I paid her the next morning after I dropped her off at her bar in Patong.
We had one more pleasant night together. Neither of us mentioned uncle...
BTW The girls in Hua Hin do the same thing almost everytime.
It is much better to talk of ST only and set a price accordingly. Some will go, some will stay for a little extra (your terms apply) or even for free.
It's a business deal: Stick with the contract.