How to reach marketing people at big companies

Hey,

I work at a company that delivers high-quality video production in affordable prices all over the world. we need to grow our client base but the problem is I can't even "get in the door" of a big company to pitch my product.

I believe that I can save them a lot of money, but how do you reach the marketing manager? E-mail's won't work... calling them either.. LinkedIn in useless if you don't know anybody related..

Any ideas?

Thanks,

Yoav