Why should i pay for something i did not agree to???

I took out a contract in September for R100 for 10G. I was charged From R1500 to R3000 and contract that i was supposed to pay R100 for. I have escalated cases from December to date and i am set from pillar to post. I have gone to the store and was told because i took it with an external provider Mondo but Telkom is the one that debits me. If i have to call the Queen of England to help me resolve the matter i need to know because my name is being dragged through the mud and my credit is lying in a ditch somewhere. I have not used the sim card since October because i was advised to do that. If someone can tell me why am i paying for something i did not agree to before i go to ICASA to take the matter further. I want the call recordings to validate how much i signed up for. Its been months and i am i have bank charges for doing that and its a big inconvenience to me. Please call me on *** or ***