Never trust Vodacom with their contracts please

I had a Samsung contract phone with Vodacom, l tried to give a notice of termination of contract because it is their obligation that at the end of the contract l have to give a notice if l do not want to continue with the contract, while I was noticing them to terminate my contract, the guy who were helping me convince me to take a new contract plan which is 15GB data for R79 per month.

We did come to an agreement for that contract plan but surprisingly the contract didn't came out on my favor, it was very bad that they recharged me with that 15GB divided into: 5GB anytime data and 10GB night owl something we did not agree about. On top of that the R79 amount that we agreed about changed suddenly to R122.99 without consulting me or asking for my approval,this ******. Now all I want is to cancel that contract and they say I have to pay penalties before they can cancel my contract. Please people never trust vodacom at all