Hi, for what it's worth, I work in customs in the UK and it sounds very much like UPS are completely out of order here. Small parcels companies regularly skirt around customs rules to make profit. If you already paid shipping, there's no freight to pay. If the rates in Canada are like the EU then vinyl is duty free. The most they could have any chance of charging you is whatever the local equivalent of VAT is and a charge for customs clearance. But, this really shouldn't happen for parcels as they very likely bulk clear a whole shipment at little to no cost.
Any way, slightly drink rant over. I work for a proper freight company that detests the likes of UPS, DHL and TNT.