What exactly do immigration at CW want from my apartment owners as proof of where i stay.

Even though ive given them (the apartment owners) the leaflet explaining it in Thai they are still confused.

Thanks in advance.

Normally immigration at CW is not strict for proof of address to get an extension for a tourist visa entry. Many reports of them not asking for anything.

No reports of them wanting a TM30.

A receipt with you name an the address of the apartment should be enough. At the most a basic month to month rental agreement.