Overcharging a cash client

I recently had to use XPS Courier services to pick up a parcel in Balfour and deliver it to Fochville. I received a call from the Klerksdorp branch informing me that my parcel (10 × 10 x 10 cm weighing a 125grams) are about to be delivered but a I was a cash on delivery client I needed to ensure that the amount of R 579.23 was available on delivery or pay it into their account. I was shocked at the amount due as the supplier said it should not be more than R 300. I then asked why it was such a huge amount. I was told that it was because I did not have an account and that the company are trying to discourage clients to pay cash and therefore charge a much higher cost. She also said that if I had an account it would have cost me about half the amount. I also requested to speak to the manager to clarify the issue. The lady said she will ask him to give me a call. This never happened. Now if that is how XPS treats clients I would never again use them for anything.