My flights on NW also typically post within a couple of days. I had one that did not, due to an involuntary re-route by NW on to US due to a delayed/canceled flight. I faxed a copy of my BP stubs and got "original routing" credit - that took a little over a week.

Sorry to hear you are having difficulty.

Do you contact SMS before FAXing your BPs?
How do you phrase your requests via FAX?