why am i being charged for a non calling sim?

I cannot apply for finance because Telkom is claiming i owe them R5500, According to Me I HAD SETTLED my bill with their debt collectors and mind you these are penalties i am paying for a NON CALLING SIM! I have already payed R12000. I have so many questions, • Kindly advise why am i being charged for a service not utilized. • Why is this resurfacing now and why have i not being contacted. • WHY CAN I NOT REACH ANYONE FROM TELKOM?