Pep Stores - Pep refuses to exchange my phone

On the 3rd of August 2022, I purchased a new phone at pep and I came back on the 5th of August 2022 wanting to a refund I was advised that it's not possible as it's for exchange only but the 7 day grace period in my opinion is a grace period regardless of the reason.. I returned the phone because it was too slow and I was told by the one cashier who works with the phones that it isn't a "technical issue" but when I use the phone google for example kicks me out and says app stopped working etc. I then left it and asked around regarding the matter then I returned again on the 6th of August 2022 stating that I want a refund once again. Again I was advised by the manager this time that I cannot and then I asked to for the area managers number which she in return said she will call him herself she then went into the room or office and closed the door apparently talking to her area manager she then returned 2mins later advising me that her area manager said the same which I don't believe because the store was not even that loud and regardless her customer service was really really bad as if it was me personally I would've phone the area manager infront of the customer. Never the less I left it and again returned today on the way 8th of August saying I would like to exchange and put it on a layby and I was told by this one lady that again the phone being slow is not a technical issue so I can't give the phone and use the it as a down payment for a layby for a new phone as I explained I would only be able to do so month end this lady then told me no that I cannot and I thanked her left.. And Wednesday the 10th of August is my last day of the grace period and I felt that they gave excuses and just pro longed this very upset. Pep has poor customer service and not helpful at all and they liars as well I don't like painting people with same brush but those individuals set a bad image for the company