Cheating Client

Last year August I took my car to Mercedes midrand for a service I was told that my front brake pads and disk needs to be replaced so I paid for brand new products only to find out now in March that the products were not new but the disk was skimmed. When I complained to them they said that they made a mistake on the invoice. The invoice says front brake pads and they actually changed the rear disks and not the front. How can we trust a large company like this as they charge customers prices for new products but we are getting cheated like this.

Regards Sohana Uddin O ********** 66