Messed deliveries

A Customer of mine put an order online and I used the courier guy to courier the order from Johannesburg to Durban. my customer received a wrong package called to report this to them and now i have to keep calling them to follow up where my package is. They don't even have the decency to call me back to tell if that they are busy with the matter, and the call centre people are rude as ****! now i look stupid and *********** to my customer, and they haven't received their package. this is not thew first time the courier guy is messing with my deliveries. i wouldn't recommend anyone to use them and i will definitely will not be using them in future.