I just extend my turist visa with 30 days in Chiang mai and it cost 1900 bath and i got it in a 1 hour,they just try to get more money out of you,go back and politely ask to speak with the supervisor
I was travelling on 60 days visa,will extend with 30 but i buy 90 days insurance but i have a return flight ticket on 60 days and will change my flight