Originally Posted by sideshow_bob

Putting a chain and cassette on is literally a job for a monkey. It takes 5 minutes and is a simple checklist. When you change any cassette, you:

a) Reset the high limit screw
b) Reset the low limit screw
c) Reset the cable tension
d) Check the b limit screw

That takes probably 1-2 minutes.

If it was me, I'd be going back to the shop screaming for completely failing on such a simple task. FAIL. After they fixed it, I'd select a new LBS.