Contract cancelled

I called in on the 19th of June to cancel my contract and was told to call on the 20th of July since I wanted to kee My number. I was then called by an agent who offered me a data sim for 99rand & I took it. That agent told me from July on I would only pay 99rand. To my surprise in June , I was topped up with the same amount that I had asked to cancel. I called was told this was because Contract was only ending in July. On the 20th of July I tried calling but there was no answer. I only managed to get hold of them on the 22nd or 23rd of July and was told that my 99rand contract was gonna be active from 27 July.i woke up to learn that, I wasn’t given the 99rand data but the same allocation that I had downgraded or cancelled. I tweeted MTN and was told someone would call me. No one did, this morning o tweeted again and was told my issue is under investigation. I want Mtn to cancel my top up contract I was on, reverse the data and airtime and SMS’s they topped me up with and give me the 99rand data I took up. I have reference number and would like for them to listen to the voice recording of that conversation and also note that I won’t pay anything more than the 99rand end of July as the agent advised.