Yu in Toronto

Purchased carpet from Home Depot & it was installed by National Installers of Barrie. Installer scratch hardwood stair when he move the carpet to the basement. At that moment, I say he scratches the stair and the installer say not making by him. After he done the carpet installation, we need to call Home Depot Canada customer service to complain. Home Depot just help us to contract to National Installations Ltd to report the case. Over a month, they still not to fix the problem. Is it not responsible by Home Depot Canada if purchased carpet from there ??? Attached scratch photo and the installation form.