Bathroom re-grout and silicone work

Hi there. I have a bathroom where the grout is poor between the wall tiles (both mould stained and places where tile adhesive shows through due to over application) In addition, much of the silicone around the bath is now mildew stained. I'd like to get it removed / dug out / redone but do I need a plumber or a tiler or a decorator for this ?