Nice to see that thier was NO scamming, and the truth came to the surface.
The Post Office is at fault here in 2 ways, for delivering it to the wrong address, and for telling you the M/O had been cashed.
Who ever told you IT HAD BEEN CASHED, should be kicked square in the A$$. I hope you get the fee back that you payed the PO, as they dont deserve a penny in this case. They should pay you, for causing all the trouble.