The Courier Guy refuses to pay claim for loss of goods.

We send a client's product that was returned to us for repairs in one of The Courier Guy's flyer bags and the unit was ****** out of the bag. The bag was delivered to our client with a hole that was made in it and it only had the power supply in. The Courier Guy is now saying we did not use sufficient packaging and therefore they will not pay out our claim. I do not understand the difference between shipping something in a bag that can be torn open or a box that can also be torn open. Both have the same risk.