Bill Shock and bad service

In December 2014 a consultant from Vodacom Direct called me to offer me a Top-Up deal on 2G Wi-Fi router. From January 2015 to March 2015 I didn't exhaust data bundles. In April data was exhausted and because I knew the contract to be Top-Up I didn't switch off, thinking that I was finishing off the data from previous month. I was shocked to get an sms from Vodacom stating that I used up data costing R6000. I called them and told how come since its a Top-Up, I was told that its an open account. They investigated, listened t the recording and confirmed that I was offered a Top-Up contract, I asked about payments since I'm not liable. I was told that they investigate further and let me know. In May R6000 was debited from my account, I reversed the payments. I later talked to accounts, they told me that they were not aware and will send the query back. Currently my account is suspended, I went to Vodaworld on the 3rd July, I waited for more than 45 minutes, to be told that Phumi, who is busy the query will call me, I haven't received any call from her till today. I don't know what to do now. Please help.