MTN Useless

I got a brand new Samsung Note 10 on the 18 May, so you have 7 days to exchange the phone when you have a problem right? NO, NOT RIGHT. I went to MTN Store in Kempton Park. Yesterday the 25 May. My battery doesn't last for half a day. My phone was checked out and I was advised to phone MTN Upgrade as I did my upgrade there. I was asked to phone various numbers. 083 135 Mtn Helpdesk, upgrade division, MTN Direct. And been told again to go back to my local MTN dealer. He phoned them. Same story. After an hour, he was told this is now 8 days and I have to give my phone in for repairs. So now I cannot exchange my phone because MTN is useless. So now I am send to Greenstone to give it in for repairs. Is this fair? No, they shuffled me around so that I cannot return this piece of **** to them