Phone can't be fixed By MTN

HELLO

I bought a Sumsung z. flip 6 from MTN BEDFORD CENTRE on a contract that was in January and in June the main screen stopped working , we returned the phone on the 5th of June and it stayed with them as it is still with no update communication to us on the phone we only got communication last week after we have sent an email and they said they can't fix the phone and they don't have parts so they will give us a Sumsung S25 plus by Friday last week even today we are still waiting for the phone keep it in mind that we are now on 2 months paying for the phone we don't have and no one seem to care what must happen for us to get the phone from MTN my emails are not being ignored and calls don't go through