Billed for wrong amount and WiFi

I took a wifi 50 gigabytes contract with telkom for R160.00 four months back but up to so far it’s stress cause they didn’t deliver what l agreed upon with them instead I’m being billed R341,70 which is not the amount l agreed upon. I was called by Sihle Mhlongo whom l took the contract with. Up to so l am not happy with the telkom service. I was taken from pillar to post with emails and calls l made up but nothing was corrected. Please help this so sad to be given such a treatment by a big company like telkom. I ended up reversing the installment but still they managed debit. If they can’t help me rather let me terminate the contract with them cause they are not delivering what lm paying for. Unhappy client.