Incorrect billing

Did a top up upgrade on the 9th of Feb and charged R37000 instead of R373. Am told it was roaming data and was given R24000 discount of that amt. I've been querying this since March this year and am being sent from pillar to post. Vodacom has now suspended my numbers and blacklisted me and requesting for R20000 on top of that for cancellation of contract(which I did not cancel). All the call centre ppl, close the query tickets and open new ones without providing an update. The shop Vodafone shop in Southgate Mall is not willing to assist with the cancellation of this debt as they say it's out of their mandate. Now am told I was due for an upgrade on the 28th of Feb, so how did they process it on their system? it's been more then 6 months now and am tired of the useless call centre ppl, where do I get proper assistance to get the remainder of R37000 cancelled?