We booked a reservation for a party of 20 to celeb...

We booked a reservation for a party of 20 to celebrate my newborn daughter's christening (an extremely significant event) on 02 December 2018. My wife first contacted Pizza by Elizabeth to make the reservation back in early October and was told a manager would have to do the booking and would give her a call back that same day. She never received a call back, yet due to her interest in hosting the reception at Pizza by Elizabeth, my wife called again a week later. This time she was able to speak to a manager and get the reservation on the books (and proceeded to name Pizza by Elizabeth as the reception location on our formal invitations). We called twice to confirm the reservation (last confirmation was on 28 November, five days prior to the event). When we arrived to the restaurant on Sunday, the staff said they did not have any reservation for us scheduled. Frustrated, my wife explained that we did have a reservation and that it had been booked a few months prior. The manager on duty argued with her that there was no reservation and that my wife clearly did not make one. She stated that if my wife had made a reservation then it would be in the system, which it was not. She told my wife that she must have called and made a reservation at a similar restaurant down in North Carolina by mistake. Insulted, my wife insisted that she did not make that mistake as she is well aware of the phone number to Pizza by Elizabeth. After several attempts to relay to the manager that we did indeed book a reservation, we showed her our phone record to prove we had called the correct restaurant. She then realized we were not being dishonest and did some research. Twenty-five minutes after our original reservation time, we had all of our party (including eight senior citizens and my wife's sister who had to leave at 3:30 for the airport) in the lobby waiting to hear if the staff would be able to accommodate us. As we were debating on whether to just leave and go elsewhere, the manager informed us that an error had indeed been made by Pizza by Elizabeth and that she had found our reservation in the system for 02 December 2019 (one year from now). She then explained that she could try and put some tables together in the lobby area if we'd like to fit our party. The staff then spent the next 25 minutes getting an impromptu setup for our group.
Around 3pm (about an hour after our twice confirmed time) we were seated and were able to start our meal. Unfortunately, the hour delay resulted in two members of our partying having to leave to make their flights before the main course was served (and missing out on cake entirely).
Before we asked for the check, the on-duty manager explained that she had removed some of the charges to express her apologies. The bill was $506 (before gratuity), so for a blunder like this I was expecting a significant discount, especially seeing as all of my guests were inconvenienced (embarrassing myself and my wife). I was surprised to see that the manager's discount for Pizza by Elizabeth's mistake was a measly removal of three appetizers from the bill (equaling $42) and no plate fee for the cake we brought in (which we should not have been charged for to begin with seeing as no one ever told my wife about a cake fee when she originally booked the reservation).
Here are my chief complaints with Pizza by Elizabeth:
* They incorrectly scheduled our reservation. I'm all about prior planning, but why would we schedule a luncheon 14 months in advance for December 02, 2019? We called and confirmed this reservation twice (phone records to prove it) and each manager we spoke with overlooked this.
* Upon showing up for our reservation, the manager on duty initially stated that we didn't have a reservation and insinuated to us (in front of our guests) that we were being untruthful about booking one.
* After doing some research and realizing the scheduling mistake, the manager offered a pathetic financial compensation for the blunder (a whopping 8% off the total bill if you do the math).