Cellphone Samsung S22 Cash Purchase @ Vodacom

So on the 2nd of August I went to one of their outlets in Greenstone Mall and purchased a cellphone cash. The next day I was traveling so I charged the phone for 8 hours as it was new as I got to my destination I realized the battery was not lasting more than a day and that was one of the reasons I had to upgrade from my Samsung S9 cellphone. The 7 days terms and conditions of purchase was not done when I took the phone back to them a week later I ha e to go check with them what how was the process going. A day later they called me back and told me they could not find any problem with the phone 🙃 so I am asking them what do I need to do as I have not had a phone I have paid for for a week already and needed a phone as I was traveling again in a day. They said they will see what they can do when the phone is delivery from their store which is not specific at all. Why do I need to be the one following up with them when I have paid for the phone in full in the first place. Latent defect of their product and all they needed to do is give me a refund or a knew phone. Why is it so hard to just get a great services from all there big services/ product providers? I am disappointed to how much pain one has to go through these days to just purchase a product in piece and get the best service through out the expensive from purchase to post purchase. As individuals/ customers go through a lot at have to always fight and be aggressive to be taken serious for a product or service have paid for like they are doing us a favor.