How do you overhaul a stem??? What, take the bolts off and add some lube, then re-torque them? Why would anyone take a bike to a shop just for that?

Also, why would you pay for the shop to install a headset when you can also do that on your own? I know you're mad, and I would be too, but you'd save yourself a lot of trouble and frustration by just working on your own bike.