vodacom playing fly by night

I had a airtime contract with vodacom which was supposed to end April 2014, unfortunately i got hijacked a day before easter last year and so my phone was also ******. After this incident i had been to the vodacom store in Mabopane central city numerous times trying to get a sim swap, they were either offline all the time or were out of sim cards and still the agent failed to let me know that my contract was ongoing, when i finally found this out i asked the question that why would vodacom keep a contract that has ended ongoing without my consent, why do i have to be the one to call them to end the contract while they were the one's who called me when they were looking for new clients. i also told them that i did not agree to such a term and they promised to investigate the matter. i have called vodacom countless times to try and resolve this matter, till this day vodacom has not gotten back to me to tell me how far they are with their investigation. what they have managed to do though is hand over the account to their lawyers who are now calling me and making demands for me to pay for a service that was supposed to have ended in April 2014, no monies is owed to them prior to April