Being overcharged on a TOP UP Contract

Why am I being overcharged? Since June 2015 You have been over charging me. I tried phoning plenty of times but the call centre was on Strike. So Now my bill is over R3000 and you suspended my service. Why am I being OVER CHARGED??? I never had issues with nashua and now i am having issues with you guys???? I am on a top Up contract so surely when my data bundles etc is over I must add new ones but I am being charged as if i am on a proper contract. Sort this out IMMEDIATELY!!!! I will not pay so much money with your F... Ups!!!! Please give me a proper explanation as to why you stuffing up my account????? BIG DIFFERENCE BETWEEN TOP UP AND A NORMAL CONTRACT!!!!!! Also i want my services activated if I get into an accident and I can't phone anyone it will be on your heads especially with my daughter in the car!!!!!!