Here’s how to request replacement accessories for Surface Duo.
Request a replacement USB-C cable or power adapter
To get a replacement USB-C cable or power adapter for your Surface Duo when it's under warranty:
Get a replacement SIM card tray
Buy a Surface Duo Bumper from the Microsoft Store or other sources
Go to Surface Duo Bumper in the Microsoft Store to purchase a new bumper. (See it in the Microsoft Store)
You can also buy a Surface Duo Bumper from other online stores that sell Surface Duo or related accessories.