Charged for 2 years of service not received!!!

I signed up for a month to month Fibre contract and when I lost my job 2 years ago I cancelled the contract. Why surprised me is that Vodacom has not been providing a service for the last three years and has the audacity to send me a bill for years of unused fiber. Please deal with this as I am still unemployed and I refuse to pay for a service that I never had access too! Kindly