Yes I see that now...sorry...read it as July 2nd......you can get a visa extension at an immigration office for 500B....but I'm not sure how long it is...possibly only 10 days. Check out
http://www.thaivisa.com
As for the trip to Had Yai...you just get a 30 day entry stamp that will take you through to departure. No cost as i remember it....just the cost of getting there. You can fly down in the morning and fly straight back after....or you could fly to Penang and come back on the return flight.
Told you thry may have shipped her out of the Province...they like to seperate people from home.....depending on the offence and the level of risk. Juveniles go to Surat Thani.