I have always used 15 minutes. I usually call back within 10 but have then spent 25 on hold and hung up on. Called back immediately and put on hold again. 40 minutes later I was told nevermind we have it covered. Granted this was with the old phone system. There was never any intent to get out of anything. However, it was a learning experience and now I'm aware of that possibility.

Go shake your fists elsewhere.