One has to wonder who the person was to whom you spoke at the shop. I can hardly imagine an owner saying such a thing (then again?); perhaps it wasn't an owner but a disgruntled employee; do you know for sure?
Also, I thought the shipping post office was responsible for deciding the charges. The way this one sounds, anybody along the line could tack on whatever they wished. And, the fact that the delivery person questioned the additional fees demanded by the PM makes me really suspicious of the PM's actions. Hindsight says you might have needed to ask for an official receipt in case the extra was going into his pocket!
Bad karma all around! Sorry it happened to you.
Jan