Dell service rep damaged my laptop

I had issues with my Dell laptop's touchpad and Dell sent a service tech to replace it.  The tech didn't know how to tighten screws and ended up stripping a screw and most likely the threaded insert on the back cover.  While working on the laptop, a plastic piece broke off and fell on the ESD mat.  The tech thought I didn't see it and quickly removed it from the mat.  I don't know from where in the laptop it broke off.  Furthermore, after replacement of the touchpad, one edge of the keyboard cover is raised and not flush with the touchpad anymore.  This laptop was new and is now damaged by Dell service tech.