The brief
The 116i had squeaking and grinding noises when braking, the kind that mean the friction material is running out. He brought it in. Squeaking when braking means the pads are down to their wear indicator, and grinding means they're past it. The discs wear with the pads, so by the time the pads are that low the discs have a lip and have lost their flat sweep. Brakes are a wear item, and there's no nursing them past the indicator, so when they get to that point the pads and the discs go together, because fitting fresh pads onto a worn disc just beds them into the same uneven surface. A service is exactly when this gets caught and dealt with.
The diagnosis
Wheels off, the front pads were down to the wear indicator and the discs had a lip around the edge, measured past the minimum thickness on the gauge, so they were done too. Fitting new pads onto worn discs doesn't make sense, so it was a set job, front pads and discs together, to reset the braking properly.
The work
The front callipers came off, the worn discs were swapped for new genuine BMW-spec rotors, and a fresh set of pads went in. The slider pins were cleaned and greased so the callipers float freely, everything reassembled to torque, and the brakes bedded in on a controlled road test, a series of measured stops to lay an even layer of pad material onto the new discs. The road test confirmed the squeak and the grind were gone, the pedal was firm, and the bite was back.
The outcome
No squeak or grind, a firm pedal, and full, even bite back at the front. The 116i went home with the braking reset to like-new. Brakes are a wear item and there's no nursing them past the indicator, so doing the pads and discs together gave the car back proper, even stopping power.