How to contact small business loan department of a bank to sell them online advertisement?

My online business provides a steady stream of companies looking for business capital and business loans. I want to contact the small business loan department of a bank, such as Bank of America, Capital One, American Express, and sell them membership (if they are a member, they can see hundreds or even thousands of hot prospects every month). How do I find the contact phone and person? I contact customer service of Bank of America but they don't give the contact information to me. Besides, should I contact their e-commerce marketing department, or the loan department, or both?|||Those companies don't need outside marketers like you to sell their services. Find much smaller businesses to market to, the ones that don't already spend millions on their own advertising.