Cell C not helpful and clueless

In January 2017,a lady from Cell C 's head office phoned me and offered me a contract for the next 24 months at a special pensioners rate in which I pay R129.00 per month, consisting of 300 minutes airtime, 300 sms' s and 300 mb data. This year on the 18 of January I ran out of data and went and bought R90 data at Spar in Nelspruit. I couldn't load it onto my phone and went to a cell c shop at Illanga Mall in Nelspruit for assistance. I was informed that I was on an open line contract and they would assist me in changing it to a top up contract. I had to answer a few questions for security reasons, then the lady asked me if someone had explained to me that I am going to loose the benefits of the first contract. I couldn't hear her clearly, so I said ok, goodbye. I did not say yes. After a lot of calls and going to cell C shops and not getting any answers or help I managed to get hold the person who first helped me, he explained that if I had heard her clearly, I would have told not to do the top up thing. I don't want to lose my 300 min airtime contract. The guy that helped me also said to the lady on the phone that I want to migrate to top up,which I didn't say, because I don't know what it means in the context of cell phone language. On the 4th of February I saw on my messages from Cell C that I only received 100 min airtime, 100 sms's and 100 mb data. They changed my contract without my signature or go ahead and now I am getting less and still have to pay the same amount and to top it off this month I had to pay an extra R170 for going over my limit which only tells me they changed my contract and still not changed it to top up. I am very disappointed how cell C treated me and being not that technologically literate they are not helpful at all and no body seems to know anything but to sign you up for a contract.