To extend your tourist visa in Thailand for an additional month, you will need the following documents: 1) Your passport and copies of the data page, most recent visa, entry stamps, and departure card; 2) The Extension of Stay Application Form (TM. 7); 3) A copy of the TM. 30 form (may not be required in Bangkok); 4) Two passport-sized photos; and 5) A processing fee of 1,900 THB.
You qualify for a 30 day extension of stay based on tourism.
>What is TM30?
It's a notification sent by your property owner/ landlord/ hotel telling immigration office where you are staying. It will look like one of the three documents below. Ask the property owner/ landlord/ hotel for a copy of the TM30 (show them the image, if required).
IF you are staying at an AirBnB, very seldom do they submit a TM30 because the vast majority of them operate illegally without a hotel license.
probably you already make it but i was do 30days visa extension before 10 days at chaengwattana and i know they did not make for me tm30 but at immigration they did not even ask for it.