If you are looking for a detailer using a polymer sealant (only stuff that will last 6 months on a daily driver) try
www.autoint.com they have certified detail shops all over the world. Its better than looking into the yellow pages....
If you do your own washing, why not detail it also? You'll save a lot more money and get the satisfaction of doing it yourself.
Black is a double edged sword, detailed nicely it look spectacular, but almost every imperfection can be seen.