Yes, Having been reporting my address for the last few years every 90 days, I went overseas for a week and was given a new style arrival card when I got back here in Thailand.

Do I work from that date on the new arrival card or stick to the reporting date on my last Report every 90 days receipt?

Yes, Having been reporting my address for the last few years every 90 days, I went overseas for a week and was given a new style arrival card when I got back here in Thailand.

Do I work from that date on the new arrival card or stick to the reporting date on my last Report every 90 days receipt?

The 90 day 'clock' starts again from the date of your latest entry.

OK I posted my 90 days reporting address form and have not heard any reply from Immigraton.

The reply is overdue, about two weeks. What does this signify?

If you posted it a week early with the stamped envelope and have not received two weeks after report due date I would contact immigration by phone or in person. Your receipt should be proof you did send it in time in the event it was lost.