4 months later account settled still appearing as if I'm owing

It's the 5th month since I settled and requested that my account be closed since I've settled all monies due. On the 4th month its still appearing as if I'm owing Vodacom their R660. I e written to them numerous times with no resolution to my dispute. I need to know where else can I lodge my complaint against them because this listing is affecting my credit score negatively meanwhile I settled their account in August. I'm sick and tired of their incompetence cause its costing me my life cannot even get hired because of this Fuvken listing.