Overcharged and no resolution

Good day. I am highly disappointed and disheartened by the service I have received from Vodacom over the past month or so. I have a problem where I have been overcharged by over R1200 on my monthly bill, no one can tell me what this is for but you took this money out of my account, which is ********. And after numerous attempts to get help I am still being sent from pillar to post with no resolution almost a month later. I have called, I've been told they will be escalated but I never get any feedback after that, I have sent emails, still no resolution. After many, many years of being a loyal customer to Vodacom, with my accounts always paid up to date and holding 5 contracts with you, I'm disgusted by this service (or lack thereof). I've had many issues with Vodacom before and have tried not to complain. But now I've just about had enough. Please can this be sorted out and my money refunded, its been a month now dealing with the same issue, and I am seriously considering leaving Vodacom because of this treatment. All my queries have been closed but with no resolution. This is unacceptable.