Terrible service

I'm a DStv compact subscriber and I'm very disappointed with the bad service I get from this company. For 4 months I've been paying R550 for my subscription instead of R385 including January 2019 but now I am requested to pay additional R52,78 top up by tomorrow the 28th. I mean I have paid more than R400 upfront and tried to explain this to them on FB messenger but it seems that they just reply for the sake of replying and not investigating. This is for the second time I'm getting this terrible service from them. M Sick and tired of this inconvenience. Why is it so difficult to verify subscription amounts paid over to them before they approach clients?