Getting ash out of carpet

[sair5412]

I had a party over the weekend and and ashtray was spilt. I carefully picked up the cigarette ends and hoovered the ash up without scrubbing or rubbing it in. I still have a dull grey mark in my cream carpet. It is only a cheap carpet (so i imagine it is nylon/manmade fibres) but it is 6 months old!!

Any ideas what i can do to remove these stains?

Thank you.