Wow, sorry to hear this. The USPS seems to be neglecting their customers lately.
Two Experiences: My mom said that she sent a package Express Mail, but she did not receive the return receipt until a few weeks after it was supposed to be delivered. Also, I ordered a package, and it was supposed to be drop-shipped to the USPS, but when I checked the tracking page, the USPS said that the left a notice (when the package did not even need to be signed for and there was no notice left either way.) I went to the website and selected to pick it up at the Post Office (since I had no clue why it was not just delivered in the first place), and they ended up delivering it to my house the next day after I had confirmed that I would pick it up at the Post Office... Very weird.
Hope she can get everything sorted and you can get your shoes! I'd tell her to use UPS or FedEx next time, as I think those may be better options for her (FJ uses FedEx itself).
By the way, thank you for your service! :-)