MTN in default

I have been billed for 2 lines on my cellphone contract with MTN which I know nothing about. I have a debit order in place for my cellphone which was debited with an extra R8200 on 1st Feb. I reported it immediately and reversed payment. I have followed the procedure given to me by MTN Customer Care and have been told that a ***** case is being investigated which will take 21 working days. I have paid my monthly contract by card. I have now had my service suspended. I am a pensioner and live alone. I am a victim of both ***** and MTN who are violating the contract I agreed to in that my monthly payment for my cellphone has been paid. They have no right to suspend my communication service until they can prove that I am liable for these new lines, which they won't as I'm not! There is no human behind their Customer Care contact center, it is entirely digital. What on earth is one to do?