Rust as in the metal is a bit brown or rust as in its flaking off in pieces and rotting?
Former.. normal, metal rusts and other than taking apart every bit to paint it or coat it that's just how it is.. latter, get it to a garage to be assessed for repair.
I think everything has some rust underneath it somewhere, even if it's a bit of surface corrosion on a rear beam for example. People worry about nothing. Try driving a 40 year old British car. Then tell me you have rust problems!