Interesting, I think, if the manager is not helpful, then there is nothing you can do from Sheraton folks,They could have helped though after other verification.

Secondly, I believe, the credit card co. have this feature, especially Amex. please call them also.

I was in Raleigh last weekend ,
stayed in LaQuinta (from expedia pkg deal) suites. One of the best values in my experience. I skipped sheraton as it was far from where I wanted to go and expensive.