Expired contract still being charged.

Vodacom have been charging me for an account that expired some time ago.i was at vodacom in Cape Town and told them my account had expired and I got a better deal with Telkom. I found out recently that I am blacklisted by Vodacom. I was at vodacom twice and they referred me twice and they told me twice they were offline. I was referred to their customer service who referred me to their legal dept who referred me to a hired legal dept call Ts legal. Ts legal could not even tell me what my account is all about all they want is outstanding money. I did not even know I was still paying vodacom as I do not receive any correspondence from them. I don't understand the logic, why must I be forced to give additional notice on a contract that ended? Why must I be forced to pay for a service I am no longer interested in. What if I am a single person living alone and died or went into a coma??? Vodacom would still continued charging me until eternity. THERE SHOULD BE A RULE THAT NO COMPANY CAN CHARGE YOU IF YOUR CONTRACT HAS EXPIRED. It is by luck that I found out vodacom is still charging me. 7 months ago I changed my account details and than vodacom blacklisted me. Only now when I want to buy something on contract I found out I was blacklisted. Someone should sue Vodacom for their atrocities. Is their someone that can do something. To put a Stop to Vodacom ******** white collar crimes. With how many consumers did they not do this to?