Cell C data contract misleading .

I was called from cell c call centre for a upgrade on my contract that was about to end . I paid R299.00 a month on top up for 10GB. Then they offered me 20GB for the same price R299 . Today on the 15th may 2018 cell c deducted R509.00 out of my bank account. They are misleading they told me that there wont be extra costs because its a upgrade and that if i should call to the call centre to put a limit on my account to stop me from exceeding the 20 GB data becauae if i do they will bill me . I never went over my data limit. But why are the billing me R509 ,i cant afford R509 a month .They ******* me into believing that the conctract will remain the same as before . I want to get out of the contract because cell c did not do as promised they have no right to just take money from my account as they want. They must pay the extra money they deducted back to me or i am forced to go to the local newspaper because they **** to me about how the payment is .

They can have their wifi router back.

Felicia