Contract sold under false pretences

I was contacted telephonically by Mondo Mobile (in association with Telkom) and asked how much I use to top up with data every month. They offered me a fantastic package with 1GB data, 1000 free sms's and free Telkom to Telkom calls (there was something else included but I can't remember) all for R99p/m. I specifically asked if I could use it with my current package with MTN and was told that I absolutely could. I realise it was ******** of me but the telesales person assured me of a multitude of benefits. I agreed to the contract and yet when it arrived, there is no way it could be used in conjunction with my current contract. I have called Mondo 4 times - the first 2 times I was assured that the contract was cancelled and that I would be reimbursed. They not only didn't cancel but double debited me at the end of November and the debit went through again at the end of December. When I call now, it's like everyone is trying to pass the buck. Firstly they couldn't find any of my details on the system - how convenient for them when I'm on the phone yet they have my details to debit my account. I was assured that they would call me back but no luck with that either. The last call I made, they told me I need to go into Telkom and sort it out with them. My question is how can a call centre employ people who don't even try and assist their clients?? I've subsequently seen numerous other complaints about the same company. JUST SAY NO WHEN YOU HEAR FROM THEM!!!!!