Taken Advantage of by a sales cellphone consultant

I bought a fone through PeP Southgate. I had R2000 with me but the fone I wanted was R2400. The sales consultant advise me to take the fone through Foneyam. I told him I didn't want a contract fone. I would rather take a fone for R2000. He insisted and convinced me said it was not a contract. I would pay off the fone the outstanding amount within two or three months. I told him I didn't want to be changed interest he said as long as I pay it within 6 months, I wouldn't and the fone would be mine. I paid the R2000 and just when I was about to pay the outstanding R400, I received a notification on my fone saying I have to pay R274. I was shocked and surprised. I called the call center I was told it was a rental fone. I then emailed them they said I had an option to cancel the rental agreement and I was given the amount to pay. I didn't pay it us I felt it was unfair the sales consultant wrongly advised me and took advantage. So I am stuck paying more than I should have paid for the fone. On top of my stress the fone doesn't even function well. I went again to Pep to take it for repairs and they told me they take a phone for repairs if it is a physical damages. The fone keeps saying UI system is not responding . I have reset the fone, deleted files and so much more . Nothing seems to help. Sometimes the fone doesn't work for days, I often have to push for a restart. I am paying for a fone that doesn't work well and I didn't ask for rental for. I am honestly not okay with this and it honestly frustrates me.