Exception to not calling Miss when snookers required?

[Souwester]

Could you tell me which two, please?

Firstly, if, when there is a clear path to the object ball with central full ball contact available, once one F&M has been called, any further failure to hit a ball on will result in F&M being called regardless of the difference in scores.

Secondly if the referee believes the player has not made a valid attempt to play an object ball he can always call F&M regardless of the scores. In other words the referee has to be satisfied that the player has deliberately missed.