DStv Blocks Viewing Because I paid them!?

DStv blocking my viewing and demanding me to pay R50 to unblock my viewing even though I've already paid R759 on the 26th of January which is the total amount I owe them every month! So basically they are trying to ***** R50 from me which I refuse to pay, and if they don't fix this problem asap and reconnect my viewing then they won't get a cent from me ever again mark my words. And FYI this is a 24-month contract and I agreed to pay a monthly fee of R759, there is no extras and I will not be paying extra.