WORST CUSTOMER SERVICE

Good day. I bought the iphone 11 preowned at game online on the 9th and was delivered on the 12th of November. I literally used this iphone for 30mins max and then it just went off and then asked for a passcode which I didn't even know. I went to the store to return it they told me that they will call me on Friday November 15th and that I should leave it at the store but I had to call them instead. Game mall of africa service sucks and I'm never buying anything ever again. They went as far as telling me that they will request a new one for me but today they are telling me that it wasn't collected since Friday since their team or whatever is not working on weekends. I am so disappointed as I'm about to leave the province soon and I have no other phone to use besides that one that's why I bought it. I then went as far as asking them to make the process quicker as my whatsapp is inside the iphone so I can't get another one and that whatsapp has work information inside. I am shattered, shattered is an understatement I'm even angry because what is this? Buying a phone cash but can't use it? No. Today marks exactly 11 days without my phone,no contact from Game Mall of africa and I've been the one calling. No one cares, no one is saying anything at this point I just need a refund.