honeybee I would just call Universal customer service..they are usually pretty helpful..and will be glad that you arent calling to bitch about Harry Potter land not being opened yet.
If your tickets are on will call, maybe they can cance your order. Universal likes making money, and if you want to upgrade your tickets they will probably be happy to help.
Speaking of making money...Universal is totally stupid with the limited softs for WW..it would be SUPER easy for them to open the park, and just keep Forbidden Journey in softs until they get the bugs worked out. Plus they would make tons in merch and food/beverage profits. I honestly don't know WHAT they are thinking over there. It sounds like they are already paying the employees to basically sit in costume for no customers... so strange!