Fradualent fibre contract

I took a fibre contract with Vodacom 5 years ago, they recently discontinued the package i had. They did inform me, however they decided to double debit me when the updagrde kicked in. The monthly installment went from R345 - R 709 monthly. I later settled the amount and they are now saying I owe them R1880 from nowhere, their systems are designed to rip people off and you cant cancel.

I want this off my back ASAP.