That' s terrible about being extorted 7100 baht. Hua Hin immigration are the most corrupt IO I have personal experience of. They also asked me for an embassy letter from the Uk and then it was an email which stated that the Uk embassy doesn't give them out. I had to drive back home and print one out. At times when I have been there I have witnessed people being sold visas by the immigration officers. They whip the calculator out and say we can do you a visa for 20,000, 30000, 60000.