I have had properties correct me for point discrepancies in one to seven days. As for getting a refund to your credit card, that should have happened a lot faster. I received a credit for an erroneous cancellation charge within two weeks of calling in to get it resolved.

It sounds like a bunch of little things went wrong, and the manager was not providing the normal customer service expected at a Marriott. You should write to the GM and highlight the consistent errors in calculating award points. There is probably something wrong with the hotel's computer program with regards to the award points.