incorrect package loaded instead of what I wanted

I have a contract with Mtn but then added another number in November 2014 onto my existing account. When taking out the package I insisted that I only want to take out the contract if it will be on a Top Up package and if not possible then I do not want the contract. They assured me that it would be on a Top Up package and that I do not have to worry and after everything they would say I would say don't forget to make it top up and they laughed saying don't worry. The guy that assisted me wasn't very efficient at all and I do understand that my contract was his very very first contract he did and I know everyone on the first job struggles a bit but it was to the point that he never knew anything what to do and it took forever and every now and then someone would just check if it's right.On Friday I got a sms to notify that I have used 90% of my credit limit of R2203 and when I called Mtn call centre they confirmed that Kenilworth Centre indeed did not make my contract a top up package as I have instructed them numerous times. . I called them Friday morning at 9am & I spoke to Riedwah who I started explain everything to & immediately she could remember me & said it should be top up