Ebay won't let you contact another member unless you are involved in bidding with them, I recently found out. It prevents members from making deals outside of Ebay and cutting them out.
I recently bought a CD off of Ebay and when it showed up, it was a four song CD sampler. I contact the seller and told him that is not what he advertised and threatened to contact Ebay. He credited my Paypal account for the full amount the next day!