I don't even think they give a toss.
If they did, they would be putting right this kind of thing ex-gratis, where the rust has not been caused by accident damage etc.
The fact that they wont even proceed under the 'rusty car guarantee(d) within 30 years' policy - is laughable.
The sad thing is - I love my car and it would have pursuaded me to buy another - but I wont be risking buying something that will rust after 3 years so they've lost my custom as well.
I wonder how many others feel the same - but even if it a large number, I imagine they find it hilarious to hear about....