Weird customer

1) "I'll call back to tell him, but can you help me to tell him..."

Weird customer: "Hi is XXX in?"

Me: "Sorry he's out for lunch. Would you like to call back later?"

Weird customer: "Ok sure, what time will he back?"

Me: "You can try calling him back at 1.15pm."

Weird customer: "Ok I'll call back then. But can you please help me to tell XXX that I will be there at 2pm to collect the software from him, I'm AAA from XYZ company, my contact no. is 9123 4567."

- Why bother to ask what time my colleague will be back and that you will ring him, when you obviously want him to call you back?

2) "Huh? You dunno?"

Weird customer 2: "Can I speak to H?"

Me: "Sorry he's engaged on the line. Please call back in 5 mins time."

Weird customer 2: "Ok. K is not in the office right?"

Me: "Yup, she's not in."

Weird customer: "You know when is she coming back?"

Me: "Sorry I've no idea when will K be back."

Weird customer: "Huh... you dunno?"

Me: "Ya.. I'm not sure when will K be back."

Weird customer: "You dunno ah...."

Me: "Yes. I have no idea."

- Why is there an assumption that people in the office MUST know exactly where their colleagues went and what time they come back?