A similar thing happened to me. I had to return a phone I bought from London. Paid extra for $200 worth of insurance, which fortunately covered the cost of the phone 100%. They "lost" the phone at the Miami, FL customs checkpoint. Waited a whole month and it never changed from "You package is moving through the USPS network." Had to file an international claim even though it never left the US. After the international claims manager looked and it and confirmed Royal Mail didn't receive it the case was kicked over to the local claims office. Then I was asked for the customs form, evidence of value, etc. I printed the documents and sent the application by mail. Two weeks later I received a check covering the $200, initial shipping cost, plus cost of insurance.
The entire process took about 3 months but I'm happy and very lucky.