Body Rust Questions

I have a ’99 Ford Contour SVT (Mondeo Mk2 body style), with some serious body rust underneath. The rocker panels (sills) are completely rusted out, so they do need to be replaced, and there is more rust underneath. Floor pans in the front need to be replaced as well, and who knows what else as my investigation continues. Maybe someone on here could give me advice about this, based on your experiences with body rust.

Hi mate unfortunately rust is like cancer the only way to do it is to cut it out buy repair panels and weld a new section in it's a lot of work and it's a different type of welding as the metal is very thin but get your hands dirty you will do it in no time

I've heard if you catch rust very early you can use rust treatment and sand off the excess but that sounds bad safety would be an issue I'd take bodgit and leggits advice