Volvo: S40 Brake pipes corrosion?, brake pipes, brake hoses

Question
My 1998 S40 has just failed it's MOT roadworthiness test for servere corrosion of the front to rear brakepipes, left and right.
However I was under the impression that these were made of a corrosion resistant alloy.
Are the garage trying to scam me, could they have mistaken surface dirt or am I just wrong in my assumption and is this to be expected in an 11 year old car with 97,000 miles on the clock. Your advice would be greatly appreciated.

Answer
Ian,
I find it hard to believe the brake lines are rusted away. I think that they are made of steel alloy to PREVENT corrosion. What about a second opinion. Where you shown what the faults were? The cars I see many times need brake hoses at the calipers, but almost never the lines. Of course where I am at there is no cold, snowy, or damp weather to speak of. Maybe just not a fault here.