Very poor and disgusting service

I bought the latest Samsung Z4 flip at mtn lakeside mall shop, biggest disappointment of my life, the phone heats up when you charging it. I returned the phone before the 7 days and they took it for testing, they said they couldn't find anything wrong with it. I took the phone and just put it away because it still gets extremely hot when you charging it, l don't know what to do anymore as l am paying for something l am not using. I wouldn't recommend anyone to buy the. Samsung though the Mtn shop as their after sales is very poor