Vodacom ********** Billing

I have a small R99.92 data contract with Vodacom which expired years ago so its been on a month to month since then. From August last year I started getting billed for a number which was not mine. After dozens of calls, hours on the phone and emails to Vodacom they eventually cancelled the number in January. The amounts which the number had incurred however continue to be included in my statement as owing so I am now in arrears. I cannot cancel my month to month due to the amount which they mistakenly claim is in arrears. Once again, after dozens of calls, getting passed from pillar to post and getting many reference numbers I continue to be billed for this amount and have been unable to receive a credit. The level of incompetence I have received from Vodacom is beyond belief, one hand does not seem to know what the other is doing and they have allowed these issues to carry on for almost a year unabated. Thank goodness I cancelled my voice contract with them a while back as I am not prepared to be dealing with this kind of inept service which continues to be a problem for me and takes up so much of my valuable time.