This happens to be one of our favorite restaurants ar WDW. I am sure I am going to get flamed but here I go:
First of all WDW restaurants in general are crowded IMHO. If you do not want to be crowded then avoid it.
Second we have always had good service here except one time and when I reported to the managment it was up and beyond taken care of. We always pay with CC and tip in cash--we have always done this. The server acted snooty at that point--but I will tell you that the Manager(Lorenzo at the time which is now back in Italy)welcomed us to come back with a full meal OTH. We did not go back for 6 months but we were well taken care of--all because of one mistake that she made.
Always order meals and wine, desserts and coffee here--and have taken guests--have not had another bad experience.
I am sorry that you had such a bad experience, but with WDW being as large as it is with all the Dining cards and ADR's this is bound to happen. Not to mention why did you not go to the front desk of your resort if you were not satisfied BEFORE you left. I am sure that it would have been taken care of in an appropate manner. And if you were staying off property then there is always guest communications.