From reading my history ive got advisories from last 2 years for 'corroded' inner and outer sills.. is this a mission of a job or could average joe do it ??
Woh..... could have been easier and way cheaper to fix when first advised. A lot can happen in 2 years, especially when it comes to rust and even worse in area's like that.
Depends how bad it is.. usually this kind of corrosion requires welding, especially if left this long.