Does anyone know if you can cross border at Ranong-Myanmar and get a new dtv entry stamp at Ranong border?

Hi everyone

Can anyone tell me how the stay extension works and what the fee is?

I understand the first stamp is 6 months, which can be extended by 6 months while staying in Thailand. Is it the case that you then have to leave the country to get a new 6-month stamp in your passport? And is this also extendable once every year?

And does anyone know what the fees are for the extension?

Thanks very much

Chris