Top up contract gone wrong

In May I went to MTN store to renew my contract. I asked for a Top up Contract phone, the consultant explained to me that I have to pay R 1 extra to make my contract Top Up, I agreed. Few days after I collected Top up Contract phone, I updated my Play station systems, downloaded demo games and also played online. After a couple of days I checked the balance, and my balance my zero and I could still make calls, send messages and go online. I then went back to the branch and told them. The consultant did not put me on top up, I had an open line contract. They set the limit that day, but there was an amount of R 4000 that incurred before they set the limit. From May until July I have been going to the branch asking them to remove this amount on my name, and they have not, they are using delay tactics to get rid of me, they told me about the USD being opened. This amount have been returning unpaid on my bank account of which charges me R 218 every time it bounces, it bounced for 3 months which totals to R 600, and is denting my credit record. I have been paying the amount of R 250 monthly, however my line is suspended. On the 12th of August, I requested to see the Manager, he came and