Poor service

I bought an Ulefone Armor X6 at New World Menlyn on the 3rd of April 2022, a week later I noticed that its not charging properly and it take forever for a battery to be fully charged, and wgeb you use it, the battery doesn't last for more than 30 minutes. I sent it back for repairs since it has a 12 months warranty. It stayed with them for a month. When it came back, I was told that the battery is fine and they only fixed the screen. So the phone stayed with them for a whole month to fix the screen. Fine, I took the phone. When I got home it showed a message, saying remove a battery, it's overheating. I took the phone back on the 9th of July 2022. When we got there, we requested to either be refunded our money or be given a new phone. The Guy who was assisting us said they will loose as a store so they prefer taking it back to their repair center. So I bought a phone in April, we are in Mid July I do not have a phone. Is this fair? My question is, how are they going to loose because they have suppliers, so they simple need to take the phone back to their supplier? Is it my fault that their phone is not working????? Uch poor service is exhausting.