As everyone else has said, yes, if you call, they will give you a credit.
To apply the credit toward your luggage fees, you CANNOT CHECK-IN ONLINE. You have to go to the airport and check them in at the counter and be sure to ask them to apply your credit. We just did this for our flight at the end of July, and I'm pretty sure if I hadn't said something, they wouldn't even have bothered looking at my account. We had $46 in credit, so we used $20 on the way out of town, $20 on the way back in, and had $6 leftover that alas, we will probably never use.
Good luck!