Corrosion and pitting on discs

[GoneAnon]

My wife has a W205 C200 Sport saloon that is just 2 years old with less than 18,000 miles. Recently there's been a vibration when braking and the local MB garage say all 4 discs are pitted and corroded.

She doesn't do a lot of miles and the car lives outdoors, but her previous A-Class had no such problems.

£750 sounded like a lot of money for 4 discs and pads so I said I'd shop around and would MB contribute? The answer back is No, due to the age and mileage (so much for the 3 year unlimited mileage warranty, then!) but they did reduce the quote to £651.

So, am I wrong to think this isn't "normal"?
Is it worth getting a price from our trusted local indy?
Or, do you think the problem might go away with a bit more regular use of the car and the pads sweeping the discs?

[GoneAnon]

Thanks chaps. Car has been used more over the last few days and she says the brakes are already much improved.

I'll take it for a pin myself over the weekend but, at the moment, I'm glad I didn't just say to go ahead.