Same thing happened to us about 5 years ago. At JFK Airport bought two bottles of alcohol and it was put in a sealed bag with the customs bill on it. We left it there to be picked up at the plane. We got it handed over to us as we boarded the plane and took it to Heathrow when we got to the customs they refused to let us take it on the plane to Aberdeen. After a discussion they said if we put it in a bag, they would put it in the hold and mark it as "Fragile" My husband emptied his leather shoulder bag and put the bottles in it.
When we got to Aberdeen the bag with the bottles was lost. After two days and lots of phone calls it was found. One bottle smashed. We were told to pick up the other one and the bag. When Phil called at the Airport the bag was ruined and the other bottle was missing, apparently, so we were told, it was cracked and leaking. What the staff did not know is, we knew someone who worked at the airport and the bottle was sitting in an office in very good order, just before the annual Christmas Party !!!
We got the money for the two bottles, plus the money for a new bag from British Airways and a apology.