HTC — damaged my phone

Address:

New Delhi, Delhi

Hello i have a HTC desire 816, i am using it from past 8 month and but recently i was facing trouble with the bottom speaker, i contacted on of the official TVS center on kalkaji road in ansal plaza and submitted my phone, after a week they returned my phone and i found scratched all over my phone headphone slot is damaged and even the volume up key is not working properly . When i informed them about the same they didnt take any action against it but they return my phone . I need amd answer regarding the same that are these service center made for reparing the cell phone or damaging it and what can be done now to get it resolved number-Q7S[protected]