Dstv unfair penalties and charges

I am self employed and living on a minimum wage. I subscribed to DSTV ACCESS R99 monthly Subscrition. As self employed i do not have an exact date when i get paid but dstv charges me extra penalties for missing the payment date now i pay R200 every month. I feel this is unfair for self employed people because we don't have an exact date of payments, this means that dstv will always charge us unnecessarily penalties instead of that they disconnecting dstv when payment date passes and reconnect when i pay again. Poor and unfair teams and conditions i did not sign on