You said that the manager was on the phone. Was it possible he was doing business? Sometimes as a manager you have to multitask. If your only complaint is that it took so long and the manager was on the phone I would say that you could have just cought them in the middle of a crisis maybe the register went down and he was on the phone with tech support. You never know. You can't let one (not so) bad expierence put you off.