benzat, my posting friend,
I have not got a clue. The wheel bounces up and down only when you brake??????? Not wiggles side to side - left to right but HOPS! Up and down, like skipping?
Sorry, friend but I wouldn't even hazard a guess. If you've replaced the shocks/struts recently there's no way that wheel should bounce. Is there a spot on the rotor that may have been contaminated by grease/oil/solvent? I mean do the physics in your head.
What would allow a wheel to bounce under the stress of breaking? It's gotta be a loose suspension part, a worn shock dampener, or a rotor (least likely?) with an arc of its circle that is nearly frictionless.
Go to another technician. The guy who's doing your work on the front end must be an idiot. The condition you describe sounds very unsafe. I can't believe a qualified technician let your car out of his garage.
Happiness is a well stocked