Bad service with incorrect information

On March I took a contract with MTN top up contract. I was going to pay R279 and get R200 airtime each month. I asked the consultant if I had an option to buy data bundles with the airtime and she said yes. I told her the only reason I'm taking the contract it because I can buy data bundles with the airtime. I tried buying data bundles with the airtime it didn't allow me to. I called he and she said she will rectify that the following month. Next month the same issue accord, I called her and informed her still she had no answer. On the 3rd month she informed me that somebody from MTN gave her wrong information, I won't be able to buy data. I told them I want to cancel the contract cause it not what I signed up for. Now there are giving me an option of a higher contract which I agreed to, but still there are taking their own time with this process. It been a week now.