It's up to the sender to make that claim Moose, it's literally on their dime that the package wasn't delivered. They paid for the shipping, they also paid for insurance I'm sure.
Your part of the equation is notifying your credit or debit card holder to stop or reverse the payment back to you.
Once the money is taken back from them you'll see how fast you get your shit delivered again.
Also, I always tell the sender (if given a hard time by them) "There's an awful lot of choices I could have made to buy my parts through!" and then I leave it at that, an open ended threat to being able to take my business elsewhere w/o saying so.......