FYI, in Jan 2013 we had a credit, but it was not on our acct. Guest Services called our TA and get it straightened out pretty quickly. Don't know if it was Disney's error or the TA's, but it was fixed.
Bottom line, at some point, check that you have it. Better earlier in the cruise than later. We stopped by GS many times during the cruise with never more than one person in front of us. The last day the line had maybe 25 ppl in it.