Can't topup data on dstv internet

I bought dstv internet after I was informed that I can top up anytime should I run out of data. 1st time I topped up without any issues. 2nd time I wanted to top up was told I reached my limit(I was never informed about limits in the 1st place) I was informed I can always top up. I stayed without internet until my next cycle. After 5 days the internet bundles were finished. And was told I can't top up as I have topped up 3 times already. Apparently I can't top up more than 3times a year( something that I was not informed again, remember I was informed I can top up anytime whenever I'm out of data). The worst part I have never topped up the 3 times that they are talking about, but only once. Due to misinformation I would like to cancel this it's becoming a nightmare as I can't do any work since the data gets finished so quickly, and I can't top up. It's frustrating dealing with misinformation by Sales agents coz the customer has to suffer. It's been a nightmare the agents tell you different stories...