The brief
The 216d had gone uncomfortable to ride in: rough and choppy over bumps, floaty, and not feeling as planted as it used to. He brought it in. Weak or worn shock absorbers cause exactly that, and they don't just affect comfort, they hurt handling and braking too, and they wear tyres and brakes faster. The shock damps the spring, it stops the car carrying on bouncing after a bump and keeps the tyres pressed on the road through corners, over rough surfaces, and under braking. As the shocks wear the damping fades, so the body floats and bounces, the ride goes rough, the car gets less stable, and the tyres skip along instead of staying planted. Shocks fade gradually so you get used to it, but it's a real comfort, grip and safety issue, so worn ones need changing.
The diagnosis
On the lift each shock got a bounce-and-inspect. The fronts were past it, weak damping and weeping, and the rears had gone too, the body carrying on after a push at both ends instead of settling in one. The shocks had all done their miles. When they've gone like that, you do them as axle sets, the matching corners together, so it was the front pair and the rear pair, fresh shocks all round.
The work
Both front struts and both rear shocks were unbolted and removed, and new genuine BMW-spec shocks fitted front and rear, the top mounts checked and renewed as needed, every fastener torqued to the manual figures. With everything back together the front geometry was checked and set so the new shocks weren't fighting a misaligned corner. A road test confirmed the ride had settled, no float, no excess sway, the car planted again over bumps and through corners.
The outcome
A composed, comfortable ride that settles in one motion, flat and stable through corners, sharper under braking, and the tyres back to wearing evenly. The 216d went home riding properly again. Worn shocks only get softer and they take ride quality, handling, braking and tyre life down with them, so doing the lot as axle sets reset the car rather than chasing the next worn one a few months later.