BAD MTN Service - Samsung S20 FE

Yet again I made the mistake to upgrade on line. Received my brand new Samsung S20 FE on 16 March. By 18 March it nearly bursns my ear off when I talk on the phone, not even mentioning that the speaker harly works. Takes it to 3 different MTN shops - all of them refuses to take the phone back since I upgrades on line. Take it to Samsung, the fault report is nearly 2 pages long. I have been sending emails to MTN online and calling non stop. No one will help me. Meanwhile I have to pay the monthly installment for the brad new broken phone for the next 24 months - OOOO and then I hear that Samsung S20 FE is a problem phone which the other providers don't even sell anymore because of this - I just want a phone that works!!!!!