Over charged by Telkom multiple times

Hello I have severely treated unfairly by Telkom. They are *********** and have overcharged me. This is from a year or two back. I stopped using their services both WiFi ADSL and home number but they still felt the need to charge me months after. And now they are messing up my credit score. I have all my receipts, emails that I sent, ref number. I refuse to pay R3000 when my Initial bill was under R1000. DONT USE THEIR SERVICES TELKOM IS A ****.