Vodacom owes me money and then puts me on ITC...???

According to the accounts department I have a credit with Vodacom for about R340, which I was unaware of as I have not been a Vodacom client since January 2016. Now when trying to purchase a car I was declined as my credit record shows that I did not pay Vodacom for 6 months and then only made a payment in April 2017. I've been trying for nearly a week now to get this sorted and I am just passed on to yet another consultant who does not get back to me, all I get is "Sorry for the inconvenience" This is more than just an inconvenience, it is my name. I also cannot see why I have to wait 21 days for this to be resolved, and if not I can take it further, I don't have that much time to play around with.