"Steve" wrote:
Unfortunatly it's over a year old as i bought it before it was
installed. Also if I exchange it I guess there's a good chance I'm
going to have the same problem in a years time. Any recommendations for
what I should clean it with? any metal polish OK? Hopefully with a bit
of elbow grease I can get another few years before it looks awful and
then i wiull definitly buy a steel one next time if that prevents this
from happening! Thanks for your replies!

The same thing happens with steel radiators. You need stainless steel or
aluminium to avoid rusting again. Even if you fit an extractor fan in your
bathroom, assuming that there isn't one now, you still get rusting.