how do i report messages from seller?

[bluefish47]

Seller sent me an incorrect item, refused to acknowledge the error although I twice sent messages with photos of the item I got and the Item I should have got,  so I lodged a refund request. Ebay  (not seller) gave me a refund.

Because of lack of response from seller I left neg feedback.

Now I get a daily message from the seller asking me to change the feedback to positive. Perhaps they'll stop after a while, but it's been going for a week so it may be automated.

Is there any way to block a seller or report messages that become harrassing?