Courier guy driver mixes up my parcels

The worst experience I have an account with courier guy for so many years and I run my small business using they service, so yesterday they driver did a collection at my property and because it was 3 parcels which we labeled with customers names to tally with the waybills so you don't make a mistake but they new driver goes and makes a mistake and mixes my parcels with it being sent to different customers so they waybills he mixed up, I call courier guy so many time but they keep making excuses that the driver says he didn't make a mistake now obviously he will say that would he blame himself, when we provided proof to show we have put labels with customers names and he mixed it up but courier Durban operations is insisting on not resolving an issue caused by a new employee.