If you have the money in bank do it yourself. Go to bank first thing in the morning get a letter and update pass book. Then go immigration get the form. The office to the left hand side of immigration will fill the form in for you if you have difficulty with it. They also make sure you have all the right copys of passport stamp from when you entered and front page and a passports size photo of yourself. Cost about 500 baht 1900. Baht total 2400 baht. Real cost including taxis would be about 3000baht . First. Some agents charge baht so total savings on that 9000baht