No record of a contract with Vodacom, but still I can't get out of it

Roughly a year and a half ago when I was due for an upgrade, I decided to not sign a new contract because I weren't sure what phone to take. Vodacom phoned me to offer me a new contract. I said I don't want to sign a contract, because I don't want to be tied down in case my phone breaks. I will look for a new phone in a few months time. The consultant on the phone assured me that I will not be tied down and that I can cancel the contract any time, and that this voice recording is available. Roughly 6 months ago my phone started giving me issues and I wanted to sign a new contract. I went into Vodacom at Gardens Centre, where I was told that they can't do anything because the people who phone you are from a different department to the store. I tried to cancel it online, and once again that consultant told me that they are a different department and they can't help me. I checked for a phone number, I phoned them and they told me that it is a different department and they can't do anything. I kept insisting because it is ridiculous it is supposed to be one company, and they told me that I need to pay out R5,000.00 to cancel - even though I don't have a device and this amount is more than just paying the monthly amount. Needless to say, I certainly will never sign another contract with Vodacom. The company is completely disorganised where the left hand doesn't know what the right is doing. These so-called voice recordings are not available, and they themselves don't even have any record of a contract but keep insisting that I do, and they keep deducting money from my account.