Mondo/Mtn

I bought a phone P40Lite on the MTN website to my surprise I mondo called me to confirmand process the purchase. The phone was delivered on 12th Jan 2021.after a week I noticed the phone had defects the screen is having lines on it, going black and white, zooming in and out, freezing and typing/pressing itself. I then called mondo the agent told me to take the phone to the nearest MTN store. I went to the Vaal Mall store with intentions to return the phone so that they can give me a reference number to terminate the contract with mondo. The lady at mtn was rude insisted that I dropped the phone (which doesn't have any scratches or sign that it was dropped) refused to take the phone as I do not have the manual anymore and said they wouldn't ask for the manual if I was bringing the phone for repairs I returned with the phone. After a week I went back to the store bringing in the phone for repairs this time to my surprise a different lady was assisting me to me that they can't take the phone for repairs because there is no manual(I even produced my proof of contract which clearly does not help) the missing manual is now used as an excuse not to take in the phone. MTN said there is nothing they can do about this. I regret buying a phone online coz I'm all alone now mondo who sold me phone doesn't want to assist too they are sending me from pillar to post. MTN expects me to pay for a defective phone that I'm not even using.