Sorry to be still flapping about cats...
One of ours pinged the 'locking' part of the flap across the kitchen after another full speed entry into the house (he was over a stone and also called Henry!).
Staywell provided a new door for a reasonable price. What you need to do it put something directly in front of the flap a foot or so away so they can't get a clear run at it. That slows them down enough for the mechanism to release while they're trying to ram their head through the hole.
One of ours pinged the 'locking' part of the flap across the kitchen after another full speed entry into the house (he was over a stone and also called Henry!).
Staywell provided a new door for a reasonable price. What you need to do it put something directly in front of the flap a foot or so away so they can't get a clear run at it. That slows them down enough for the mechanism to release while they're trying to ram their head through the hole.