Welcome to the Cake Decorators Q&A

what kind of flowers and colour should I use on a white black and silver themed cake. customer only wants these colours no others. just wondered what kind to do

That sounds lovely! I think I would make one big statement flower in hot pink. All the flowers can be seen here:
http://www.cakeflix.com/online-cake-decorating-course-category/flowers
Lets see what other members come up with!

How about one large black flower with silver highlighted edges on the petals? I made a black flower with gold highlights for a black, cream and gold cake and it came out beautiful. See Pauls tutorial for this gorgeous black flower – www.designer-cakes.com/online-cake-decorating-courses/gothic-lace-vintage-cake