This is (alledgedly) the transcript of a customer services call to a well know travel operator:

Customer: "I've been ringing your call centre on 0700 2300 for two days and can't get through to enquiries, can you help?"
Operator: "Where did you get that number from, sir?"
Customer: "It was on the door to the travel centre."
Operator: "Sir, they are our opening hours."

Personally, I blame the 24 hour clock!