I'd institute an "award" for being a diver, cheater or something else related to unsportsmanlike behavior on the pitch for each match. So it will be like "man of the match" awards, but the opposite. It will be given not to the worst player, but to the worst behavior on the pitch.
Rather it will be the opposite of "fair play" award. This will, I hope, discourage such behavior on the pitch. Also, players will take more damage to their reputation, and lose following/contracts from businesses, and hopefully, that will fix their behavior.
This is needed in Spain especially. Players are bad with their play acting, and fans are worse with their support for such behavior.