The easiest solution is to go on a Cambodian visa run which shall give you 30 days more. It is important that you have a visa run agent check your passport before you book a visa run to make sure you are eligible for the 30 days. In most of the articles I write I try to advise people that if you plan to stay more than 30 days when you come to Thailand, don’t just bring your suitcase, make sure you obtain a visa from a Thai consulate in your own country before you arrive, it does save you all of the hassle.