User Activity

I want to to block a seller from contacting me. I have not purchased from this seller, now would I now. Please help
I NEED TO KNOW, ASAP, HOW TO CANCEL A RESERVED BID. I SET RESERVED BIDS ON SOME ITEMS I DO NOT WANT.
Can anyone tell me if it possible, and how I can change my reserved bid??? I ask becaause there are some items I have placed reserved bids that I no longer want. And am hoping someone will outbid me:) Thanks,
Helpful given to