I think that I mentioned in another thread that I had purchased an AP voucher for myself for DIScon 2002. When we did a last minute July 4th trip this year, I didn't have time to get vouchers for the rest of my family. We went straight to the International Gateway at EPCOT when we arrived at WDW and I turned in my voucher for my AP, then bought AP's using the Disney Club Discount for the rest of my family. Having the voucher didn't make one bit of difference in this case. In fact, the CM messed my last name on my AP (which I had corrected at MGM a couple days later). I guess the only advantage to having the voucher is that it locks in the price of the AP. One other good thing was that, when the July credit card bill showed up, there were only 3 AP's on it instead of 4.
Good luck straightening out your voucher. Rest assured that they can fix it when you get to WDW if they don't correct the problem before you leave.