If you still have the money pack and the receipt greendot will refund your money and deduct the fund from the user who deposited the code and that deposit account will be closed.
Little update:
I contacted Moneypak first thing in the morning. Pretty much just said that number must have been stolen. They asked simple questions like:
1. Did it look like the moneypak had been tampered with when you got it?
2. Did the cashier look suspicious?
3. Did you give this away to a friend?
I had to fax them over the receipt as well. Was told I would hear back from them in 5 business days UGGGGGGGGGH.