Incorrectly Billed

I took a tablet on contract at Game stores, the contract read 500MB SmartTab 3 for R49.00 Top up on 3 March 2016. On March I realized that the line has been opened to make unlimited calls i called in and they couldn't find the problem I insisted until the problem was picked up that it is not a Top Up as it said,it was actually opened to make calls. I was very disappointed because this was not the agreement i signed for but they assured me that it is sorted. This month i was billed ridiculously i phoned the subscription line on 28 April the person who helped me agreed that i was incorrectly invoice and that Vodacom will refund me the money within 24 hours .On the 30 April I called in again because the guy promised to send me the Reference number but did not and a rude lady assisted. She told me I must go back to Game stores as they cannot help me, i have been billed correctly. The attitude of this lady doesn't qualify her to be in customer service. Since i couldn't be helped i went to my bank to reverse the debit order as i refuse to pay for something i did not contract for. My agreement with Vodacom for this contract is a debit order of R49.00 which the 500mb is a package and should i need airtime i will buy myself i never asked for any airtime nor smses. If Vodacom cannot assist me, it is better we cancel this deceiving contract. I refuse to be milked at my expense. They shouldn't falsely advertise things to lure customers if i knew i would pay R269 pm i wouldn't have taken this contract, cause this tablet is not worth my R269. Until vodacom decide to bill me as per our agreement i would keep reversing my debit order