Pep Stores - I was sold an itel phne under false pretences

I needed a new phone and went to a PEP store in Northmead Mall Benoni. I am with the Vodacom network and told the saleslady I was interested in phones manufactured by Vodacom. I liked the look of the Itel and asked her if it was made by Vodacom. She said it was and showed me the Vodacom logo on the packaging. I bought the phone but from the first time I used it I could tell that it was extremely slow even lagging for up to 30 seconds (which I timed). The screen also kept freezing and had to be rebooted frequently. Not being happy at all I went to my nearest Vodashop to see what the problem was and could it be fixed. Imagine my surprise when they informed me that the phone was NOT made by them but only used their network. By now I was really angry and returned to PEP to tell them what Vodashop had said. They admitted the phone was not made by Vodacom and also that they knew the phone was slow (having had complaints from other customers) but told me that there was no basis for replacing my phone. I feel that I have been duped and sold the phone under false pretenses (basically I was lied to by the saleslady) as I would never knowingly have bought a phone not made by Vodacom, whose phones and network I have used for years. I have also bought many phones from PEP over the years finding them reasonably priced and have always received good service but now I feel like I have lost trust in PEP stores