While I agree you should get your refund faster than that I have to point out that, even with express shipping, ordering something four days before your wedding was cutting it close. This is especially true since you placed the order on a Wednesday and needed it by Sunday. Many shipping companies don't deliver on Saturday and Sunday. Some deliver on Saturday but only in the morning.

Another issue here was the major storm in the Northeast on the 14th. Even if you weren't in the storm area, many shipping companies were backed up because of the delays caused by it.