Went back there again this morning. They still can't find the parcel! Waited about 50 minutes whilst they rang a few other nearby POs without any luck. It should be a great big box, they can't miss it surely.
Once something similar happened to me when I bought my AM-19 Unicron the seller I bought it from wrote his sir name instead of mine on the box and they spent around half an hour looking for it until they noticed what happened.