Cannot exchange phone

Good morning. On Sunday the 11th if July 2021 I went to buy a phone Nokia C10 at Pep Home in Protea Glen Soweto. When I got home, I tried to charge the phone, sometimes it does charge, sometimes it does not charge or it says charging slowly and it keeps on jamming. I went back on Monday to try and exchange it but because of the looting happening in our country I had to come back. I called their customer care to report the matter and they gave me an email where I should report the matter and they haven't responded since Monday. I went to one of the pep stores at Princess Crossing to report the matter and they tried to assist me, and they told me the cashier gave me the wrong slip that didn't show the date it was purchased, rather she gave me the slip written printing error. They then said call pep customer care and tell them the slip doesn't have the date and if they want to speak to us, we'll let them know the same thing, so they can search from their side if you give them the IMEI number they will know on which date you bought the phone, so they can be able to assist me. Instead one of the customer care agent named Maryane said the store Manger should call the Area manager and she did but the area manager refused because the slip didn't have any date it showed printing error. Now I can't change the phone because of the mistake that the cashier did, and also it only has 7 days warranty that is going to lapse on Sunday. And cashiers at princess crossing did say they can check with IMEI number when the phone was purchased.