Talked about this in another thread but I thought it deserved it's own.

Concerning entering an instance that is already completed:

This has happened to me and I know how it happens. After completing the instance a party member leaves. The leader of the party gets the pop up for replenishing. I've received it myself. I always make sure to press no. I bet there are individuals that hit yes just to grief...or possibly by button smashing.

I've been summoned twice to AK that was over.

Developers need to shut down the ability to replenish when the final boss is defeated.