Cell phone error

I purchased Samsung s10 note lite in feb as an upgrade, the phone is now not working, I refuse to have a phone over 600rand that is already having problems in the second month of purchase, what is frustrating I couldnt be assisted during lockdown I was told to hold until shops open and send the phone to Mtn, Now I have taken the phone to MTN and they are refusing to take the phone, they say I must call MTN to collect the phone,,what does that mean, this is mtn at carnival mall,, I need this sorted asap can I be incontact with a top manager at MTN, I would please like to receive a new phone asap, I cant be sent from post to post,,, and i cant have a damaged phone within 2 Months, the phone has never been fallen or incontact with water,,,,,,