My exhaust is slowly dying, despite me desperately patching it up a few times 
.
It's a fairly old car, Citreon C3 2006.
The back box has a large hole in it which is growing due to rust.
Does anybody know roughly how much it would cost to replace the back box? Or the whole exhaust system?
I'd try to replace it myself but I've never had to replace an exhaust before and it looks difficult.
Thanks