Poor quality devices sold

Good day,I purchased three types of cellphones at Ackerman's connect shop no:3000 in mams mall Mamelodi on the 19th of December 2023 for my kids. Today I went to return one cellphone itel A14pro for R449.00 because it's very slow, battery heats up and I can't download anything. I was told by the manager Jennifer that they know about the phone it's slow and you can't download anything with it. My argument was did she mention it to the head office or area manager about this,she said no. How could they sell cellphones (devices) with such poor quality I mean it's day ******* and they expect me to keep this cellphone and just accept the quality after I paid for it. No it's not fair I need a different phone or refund! I even told her that I will add money so I can exchange the cellphone she refused on the spot