What to do when dell won't fix or replace the laptop when under warranty

We bought my son a laptop for college and it has been nothing but an issue.  He is responsible and takes care of it properly.  He was told to take it to a local repair shop that supposedly fixed it, but within one day it's back to randomly shutting down, and several keys do not work.  What can be done?  It's ridiculous that dell takes no pride in honoring their warranty.  He's trying to get through his college courses and finals with no laptop.  They should replace it or send a borrowed one until they can repair it.  I've been a loyal dell customer, but this may be the end of my dell days.  Every time he calls dell they are no help, no supervisor available and tell him just to go back to the repair shop.