MTN Pavilion Westville (Big store) has my phone for 8 months

Good day all. MTN Pavilion (Durban Westville) My samsung phone that was only 6 months old stopped working. I gave the phone back to mtn for them to fix it, has it is still under warranty. The phone was given on the 21/08/2022. Now it is 02/04/2023. I have not received my phone back and i pay for it every month. I have been to mtn about 20 times. They're keep telling me the phone is not with them.

Can someone please help me get my phone back. Thank you