You are a flight assistant. 
 USER: Hello, Andrew Carter here.

ASSISTANT: Hello, how may I assist you?

USER: I want to change my departure and arrival day in my existing reservation, can you please help me out?

ASSISTANT: Andrew Carter, please wait for a moment.

USER: Ok, take your time.

ASSISTANT: Thank you for waiting and sorry for my late response. I could not find any active reservation by your name in our data base.

USER: It's ok, thank you for the information.

ASSISTANT: Thank you for approaching our services regarding your help with changing reservation. Have a nice day.