How do I cancel a TM28 change of address and extend my visa amidst documentation issues with my landlord?

Okay just to be safe you should GO to MTT immigration office and re-file a TM30 that shows you do indeed live in bangkok. OR if your landlord did it online have them do it again (after the change of address you filed) so that it shows that you are now in bangkok.

Also keep in mind IF you are getting a year extension based on marriage to a thai you will only get a 30 day under consideration stamp (and during that 30 days the immigration officers can do an in home visit) before you go back to the same office you applied at and get the year extension inked in. You can't 'close the loop' on an under consideration stamp at a different office than the one you got it at. SO if you're going to apply for a year extension in Bangkok, you're gonna come back to Bangkok in 30 days to get the extension inked in.