We know there are computer issues at WDW. I've stayed off
DVC property at other WDW resorts and had to supply all of the names on the reservation again or had to add names...and this was prior to the dining plan.
What I think could be a simple solution-mail a confirmation with all people's names on the reservations and on any present/future plans like Dining. If there is a problem at check-in, give the person your copy of the confirmation, and go enjoy yourself, while they straighten the problem out and don't hold your vacation hostage. You shouldn't have to stand there while they get computer A to talk to computer B. And they have all the info they need on the confirmation letters.
The $1500 charge has never been an issue for me, and I've gone over it many times on property. That is poor training resort wide. That credit card just needed to be cleared. There should have never been a denial. The OP goes out of the way to criticize the WL, and praise everyone else at WDW, but this is an example of where it was a problem outside the WL where they didn't do things the way I've always been dealt with.
This just seemed like one of those trips....it happens. When there was no record of the P&P party or the Grand Gathering event, it was no big deal. Everything else was a major screw-up by the WL. These people are subject to the limits of the computers that they work on.
The computers are one of the major sources of irritation resort wide for me. I've had the 'glitch' at midnight where we walked into someone else's room at Coronado Springs. Luckily they weren't in there at the time, but how two people can be registered to the same room is beyond me.
One thing I've personally never ran into at the WL is people who are dismissive and or unfriendly.