Telkom bill

I took a business contract for 24 months. My business failed due and I was stuck with this contract. I paid R300 over 2yrs now as agreed as Im unemployed. Iunderstand I owed them R26 000. But how do I finish it when the interest is ****ing me. I have been paying this into their attorneys account for this period and today I received a call from another attorney stating that we now have to make payment to them as the matter is now handed to them. They want me to pay R18 000 by end of this week. My telkom invoice shows I'm owing R12 770 till date. Need assistance in the right direction as I will be paying this for life. All is money for a service I don't even use Thank you