Been sold a lemon
 

I bought my car a couple of weeks before christmas and yesterday i took the sill guard off the car and discovered that the sill has rusted through completely and the car shouldn't actually have been sold to me or be on the road at all. I'm just wondering if the law is on my side and if the dealer i bought it from is required to fix it or give me my money back because the car should never have been sold in the first place? (whether the guy knew about the damage or not)

Seek detailed advice about how to reject car from Trading Standards or similar before you go back to dealer. You may need to get a report from a qualified engineetr

Major rust is a reason to reject the car not to seek to have it repaired

I spoke to the guy and he said bring it back and we'll get an independent mechanic (i'm hoping he can get the AA or RAC to come out to do an inspection) to look at the rust (i'll post a picture because i don't doubt for a second that the mot is now invalid) and then we'll decide what to do, from my understanding repairing it would require a whole new sill to be put on the car (not to mention whatever undiscovered damage there is on the other side) would cost many thousands so it seems more practical to just give me my money back. so are you saying that somewhere i have a legal foot to stand on?

It wouldn't cost thousands to weld a replacement sill, you are looking around £60 for the part and a few hours labour charge - Mike

But it would just rust around the patch and become a problem again in 6 months

Not if its done correctly, a replacement sill is what I said not a simple patch.

To be honest if its as bad as you are making out how come you bought it in the first place? - Mike

Don't see how anyone can have known about the sill unless there were visible signs with the guard on. MOT tester wont have been able to check properly with the guard on as they are not allowed to dismantle parts.
Hope you get it sorted with a whole new replacement sill, though if the patch is done right it will be fine.

That's my problem, he could've been just as surprised as i was, attached is a picture of the damage to the sill, the other 4 holes for the the plastic clips that hold the sill guard on have also started to show signs of rusting, there's also significant damage to the wheel arches and some rust i've discovered under the car. my main problem is that i don't want him to repair the car, it's been nothing but problems since i bought it and i don't really trust him to do any of the work properly.

your finger will go through that main patch and the rest of the sill is much more 'bendy' than it should be

That's the kind of image that scares me. It's all nice having these covers but who knows what's happening under them till it's too late. The sills are an integral part of the structure of the car and when they go the driver is sitting in a death trap.