To shun a player from your table (and avoid private messages from her/him too) you can add her/him to your blacklist.

To add a player to your Black List, open their profile and click on the black triangle symbol with white exclamation point:
Only a VIP member has this function.

This message will appear:
Enter the reason using a minimum of 1 and a maximum of 10 characters.
Please note that this motivation does not serve the Staff of Burraco and Pinelle but it will serve you in the future to remember why you put this user on the Black List.

Only vip users can use the Blacklist (please chech the vip subscription).
A maximum of 500 players can be entered in the Blacklist.
Once you have reached the 500 players, to insert a new player you will first have to remove another one (and here the motivation you gave will be useful) as explained at the following link.