Bad Samsung customers service on product warranty assessment

My samsung galaxy s24 ultra fingerprint screen lock makes it rebooting it's only few days old so MTN acknowledge the issue n send it to samsung but they keep sending back my phone without fixing the problem or replacing with new device MTN at liberty mall pietermaritzburg check the phone n said but phone still faulty n doesnt comes on if you put fingerprint screen lock... passed 2 month MTN sending phone to samsung and samsung sending phone back to MTN and problem still not solved from passed 2 months .. As a MTN customer I'm still paying for my phone without having phone i have lost all my data. I had to take new contract phone to use the phone.. I was not expecting this from samsung after being loyal customer from passed 17 years. Im still hanging in between samsung and MTN Without my phone. Is anyone there who can help me