Telkom Contract, having to pay for their fault.

I sign up for a smart internet contract two years back and i did this on their website after that an agent called and i completed my contracted. After a year or two I get a notification that my contract has been terminated and have to pay 3000 Zar, I logged a complaint and found out that the agent who helped me used a closed banking account details which i never gave her because i used i gave her the banking details for other contract which i have with telkom. And now i am ordered to pay R3000-00 for a fault that is not mine. I logged complaints with Telkom but no help ...ombudsman can assist ?