I just converted from a Visa exempt entry to a non o visa and than added a 1 year extension using an agent
Look at what visa ur on, Is it a NON O or>>>>>?
IF you hold non O you can get the RE extension ( if you have the 800,000 in the bank or can show an outside income of 65,000 baht/month) at any immigration for 1,900
you will need to have filed a tm 30 as well
if you dont, you can convert in Thailand for 2,000 baht
If you travel to another country you will need show 800,000baht or equivalent in ANY bank to get a single entry 90 day non o