Here are some things to do when something like this happen. Following this can go a long way into smoothing a bad situation. Being pro-active goes a long way in calming a buyer, who just wants to be made whole. There are plenty of threads out there showing how people are scammed in eBay, sellers and buyers alike.
Once you noticed a delay, or tracking is not updated within a certain time frame, submit a "where's my mail query" to carrier and notify buyer. Sometimes this tend to "loosen up" the package and move it along its way.
If you are forced to refund, due to parcel not moving, you can always contact carrier and have the packaged re-directed/intercept to you. USPS charges $15 for this service, not sure on UPS or FedEx, but I presume that you do need to have an account with them, and might cost the same or more. You need to determine i this cost far outweighs the loss of package
If unable to intercept/re-direct due to cost or maybe package miraculously is delivered after refund, politely contact buyer and advise then that u see that packaged was delivered, a bit latter than usual, but you will like to at least receive payment or have the item returned to you. The buyer is in no way supposed to respond, but maybe they are honest enough and agreeable to this.
Good luck.
