Vodacom

I had a vodacom Fibre service that I specifically requested on a month to month basis.Before signing up, I confirmed that I would be able to cancel at anytime without penalties, and I was advised that this was possible. After canceling the Fibre service, I opened a new Vodacom contract. However, I am still being being billed for the Fibre service that I no longer use. I was informed that I am liable for the charges because the billing had already been processed. I do not understand why a new contract was opened while I am still being charged for a Fibre service that I had already canceled. I cannot afford to pay for both the new contract and a Fibre service that is no longer active.