CC not working properly. Champions still able to use abilities.

In a game today we noticed that champions were using abilities through an Amumu stun and blitz after being charmed from ahri was able to use his pull. There were other times during the game that stuns were not working properly and they were not as obvious as the two I mentioned.

They didn't have banshees veil and they didn't have any item to mitigate the CC.

Also when Garen ran past an enemy turret, the turret instantly lost 3/4 of its health when it was taking NO hits from mobs or champs.