Car vibrating after new tyres being fitted

Check the wheel nuts are all tight for a start.

If it was a reputable garage they should have balanced the tires.

Perhaps you need the cars tracking checked.

Were the old tyres worn on one side?

Probably not balanced correctly ! Also when I get new boots I always get a four wheel alignment ! Also make sure the "outside" on tyre is outside , surprising how many installers don't adhere to that !

Nah. A new lad would be trying to impress. At it a few years and can’t be bothered, I’d guess.