FedEx charge overnight rate and deliver a week later

My transporter sends invoices via FedEx overnight from Durban to Johannesburg. On two occasions the documents were only received a week later. I have spoken to the supervisor on duty at FedEx and explained the problem. They apologised to the customer (me) in Johannesburg for being late. They have not for the last month and a half contacted the Durban client to apologise for delivering documents late and *****ing their money.