Phone tradein rejected without any proper reason

Hi Team,

Hopefully someone will listen here . Please find below the events as per the dates :

01/07/2025 - I have added a new line with new iphone 16 pro max from Sunnyvale, CA xfinity store. In return gave my old iphone 15 pro in tradein deal where the store guy registered the old phone with I[Edited: "Personal Information"]. ( iphone 15 pro has [Edited: "Personal Information"] ) 

01/14/2025 - I had sent my old iphone on the label address through USPS tracking number [Edited: "Personal Information"]

01/21/2025 - I got know that tradein got cancelled because of the serial number mismatch and the phoen will be ship back to me . 

01/21/2025 - After multiple followup with xfinity customercare to stop the phone way back to me and requested to ask the required team to verify again. Raised a ticket [Edited: "Personal Information"]

01/22/2025 - 02/09/2025 - Tried to reachout to xfinity customercare to know the status of my raised ticket number. [Edited: "Personal Information"]

02/10/2025 - I have received my old iphone 15 pro without the phone original box .

02/11/2025 - I went to xfinity shop to get the details however they didn't help because the ticket is still open.

Till now more than 20-30 times i have tried to reachout to xfinity customercare over the chat and call however no proper response received and everyone asked my issue and accordingly i repeat my tradein issue from beginning. 

Backend team working .....that the response got from everyone . Customercare Team also  suggested to check with assurant but without any claim number they can't do anything. 

Would you please let me know what to do here ? Appreciate your assistance to resolve this issue as its a headache from past 20 days and mental harassment. 

Regards,

Sailendra