Vodacom terrible service

Vodacom's service (or lack there of) is absolutely terrible. They have been deducting money off my account for the last 10 years on a contract that should have been cancelled but never was. For the last two months i have been asking them to cancel this contract AND requested a refund since the contract in question was never used after it ended nor was there ever an attempt to renew or upgrade it. They have now cancelled the debit order (which i'll keep an eye on) but refuse to help on the refund side.. I have emailed asking them to help me on this.. But all i get is a reply saying " Please provide the ref no for the cancellation" So after i reply saying it was 10 years ago, i simply get ignored.. I don't have a reference number as it was 10 years ago ( Who keeps a reference number for 10 years ? ) So i get no feed back for days and when i email AGAIN all i get is the same reply " Please provide ref no of cancellation" They are absolutely useless and refuse to help on this matter and i am very frustrated as no one is willing to help, BUT they will happily take your money every month.