I did a web search for WM corporate, sometimes it will give you the general WM page, nothing to do with corporate.
If you put into the search Wal-Mart CEO, you have a better choice.

I got to a customer feedback page that you can fill out and send into corporate.

Here is other contact information

Mr Lee Scott, CEO
Wal-Mart Stors, Inc.
Bentonville Arkansas
72716-8611

phone 1-800-925-6278
journalist 1-800-331-0085
stock information 1-800-438-6278

Thanks Ken.