Passing the buck on the theft of cash

In September 2014, I visited the Vodacom shop at Melrose Arch to purchase a dual sim card to use up my package of 3gig per month of data, in my iPad. I was perfectly clear to the salesman, having been ********** so often before, I was assured the additional cost would be R9.00 per month ONLY, with an upfront payment of R160.00. In April I discovered that I was being charged an additional R100.00 per month for the dual sim card, the total cash loss to me being R700.00. Vodacom told me I should lodge a complaint at the store, which I did. They gave me a load of guff about how Vodacom will refund me once they submit the details on my behalf. I followed up with an email to Vodacom, which was subsequently ignored by them. Quite rightly, I have withheld any further payments until I have recovered my R700.00. After follow up complaints, Vodacom have now made this my problem, telling me I have to recover the ****** money from Vodacom Melrose Arch. BUT, they cannot tell me the name of the owner of that store, or even the telephone number!!! Vodacom, I WILL NOT be bul**** and will not make payment until I have recovered my money. YOU get it back from your trade partner!