8ta Sold my tablet that Im paying for every month

On the 24th of August 2013 I took a tablet contract (Samsung 8) with 8ta. my girlfriend Venice Theunisen took the contract on my behalf because they wanted someone that was working and had payslips, so they debit the money R473 from my girlfriend and I pay it directly to her. Last year around June my tablet started giving problems with the battery that did not last after being charged. I took it back to the shop towards the end of August last year, and the salesman Syabulela confirmed that they will fix it for me at no cost. two weeks later I received an sms from the repairs shop stating that I must pay +-R770 for the phone to be repaired or R188 to get it back. I went back 8tA, asked them what is happening, and they told me there is nothing they can do I have to pay, the salesman that was helping me is fired. I called the head office, they promised me to call the 8ta branch in Hatfield and instruct them to email the repairs company and claim back my tablet that I am paying for every month on behalf of the shop. I went back to the 8ta shop and called them many many times. eventually they told me my tablet is sold. they are taking me from pillar to posts. please help me