Car repairs

Took my car to the garage because there was a noise when I turned the car. The guy said he thought it was my ball bearings. Took it in and when I went to pick it up I was told that it wasn't the ball bearings but shale in my wheels. I have a 2010 Toyota Aygo and live in a town so I thought the was strange.
Got the bill today it is £105.
Says they have checked it over on ramp for bearing noise. Trace fault to corrosion on brakes, strip, clean & grease.
Have you heard of this problem before? Do you think this is a reasonable price considering no new ball bearings were needed?
Thanks