Missing account which affected my credit record!!

I had a phone contract with Vodacom which I was paying, however it went into arrears because I lost my Job at that time, when I began to work I then started paying it off. A couple of months later I went into the Vodacom store to find out what the balance is to pay off and the store assistant said that I've never existed with Vodacom. I questioned it because I knew I was paying the account, the store assistant then assured me in saying that \if we cannot see you on the system that means that you don't owe us money and you don't have an account with us". I believed them like an idiot and months later I do an ITC credit check and my Vodacom account is in arrears. Now this is unacceptable and for the self-proclaimed best network in South Africa has now messed me around and set my life back for a good couple of months. I would like to apply for a house"