So upset with Telkom

I'm so frustrated with telkom who keeps on deducting my money and yet I do not owe them, I had a router contract with telkom which came to an end they offered me an upgrade I took it but only upgraded a Sim not a device, after that upgrade it had no internet connectivity when I went to them they advised me to cancel the contract since it cannot be fixed. Now they charging me for the device they never gave me. They keep on deducting my money anytime they want and I've tried fixing this problem at telkom stores with no help. I really don't know what to do anymore