PAYING FOR DSTV MISTAKE

Just wasted over R400 in airtime trying to connect my pvr services after price lock expired after 2 years they tell me that all this time i have paid in arrears not advance though when switching over to pricelock i transferred all credit to them. they refuse to reconnect my services till I pay R1841.73 for their mistake. How is it that they just get away with cheating people out of their money. the more i ask to have the matter resolved the less answers i get and more but's can someone please help me AS I HAVE NEVER BEEN IN ARREARS EVER WITH MY DSTV ACCOUNT