********** by Postnet!

I went to Postnet in Franschhoek today & was told that my purchase was below R 50.00 on a credit card & would result in R 5.00 being added to the cost! Surely this is not legal! I confirmed with Postnet in Paarl & was advised that they did not charge the extra R 5.00 The result of these charges would be that Postnet are profiteering our of customers using a credit card!