I was issued a one year extension on 20 October, today I went for a 90 report and was fined B2,000. There is a document in my PP saying I reported my address on October 20. My wife and I both remember asking about it and being told it was OK, come back in 90 days.

Was it your first extension application? If not it did not change your report date unless they put a new receipt for doing a 90 a day report.

When was your previous report due?

Perhaps the receipt you have is a for a TM30 report you did.

A 90 day report receipt states this on the line under your name. "HAVE RECEIVED NOTIFICATION OF STAYING IN THAILAND FOR 90 DAYS FROM"

It was my first extension, the thing is we definitely checked that it didn't need to be done last time, all we needed was notification of change of address. 

Evidently they are incorrect if October 20th is the day you applied for the extension. January 17th is when your report was due. You can do it up to 7 days after the report date without being considered late.

That's what I thought. It's a small provincial office, less than ten ppl. The guy who fined me is the same guy who came to my house and the same guy I notified the change of address. We definitely discussed the 90 days and it didn't need to be done, nonetheless today I was fined B2,000