Bad service

Wow you can't complain about the service you get from mtn because there is no service... got a brand new samsung a 32 5g that does not pick up a simcard i tried to take the phone back they said they cant take it back as the system is down i emailed the complaints department and still no answer. Mtn must come collect the phone and provide me with a new phone i they you expect payment every month but dont care about the clients