I think they need to implement a card or flag system for the managers in the style that NFL coaches get here in the states. Each half they get to challenge one call they disagree with. But, if the ref’s call stands, there would be some punishment for the challenging team (maybe a yellow for the manager and the possibility of being sent off if they lose both challenges). If the ref reverses their call, advantage gets played to the team who challenged the call (offside call gets reversed, yellow/red card challenge gets overturned, penalty given, etc).

I think penalizing players who “wave an imaginary card” is definitely something that needs consistent enforcement, as others have already mentioned. But, that goes along with all the officiating. Consistency is the request from fans.