Billed over R6000 in one month

I am currently a vodacom customer who was contacted for an upgrade to my current top up contract, which I agreed to. Was contacted by one Tshepo Mokoena ***) regarding the upgrade. We agreed on a top up R200 contract on my vodacom number ***. That was around the 20th of April if I'm not mistaken, but on the 28th of the same month or early the following month, I receive a message that says that my unbilled usage amount is R6237.20, which did not make sense to me until they did actually deduct it from my nbank account. I then proceeded to the bank to reverse the amount, but they deducted it again and to top it off they blocked my line. I am a month without a phone and keep being sent from pillar to post about my money/account. I want my money back and phone unblocked as I am a loyal vodacom user. I'm even considering going to the ombudsman but was advised to start here. Please assist