You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Suddenly the planned trip got postponed, so that I decided to change the travel dates in my previous ticket. Will you please help me with the changing the details of my ticket?

ASSISTANT: Sure, I am here to help you with that. Can you please tell me your name?

USER: Thank you. My name is Nicole Brown.

ASSISTANT: Ok, can I put the conversation on hold for a minute?

USER: Ok, take your time.

ASSISTANT: I regret to inform you that, I have not found your previous ticket in our chart list to modify the details.

USER: Oh! That's not a problem for me. Anyways thanks a lot for spending your valuable time for checking my previous ticket status.

ASSISTANT: You are welcome. Thank you for choosing our flight ticket booking agency.

USER: Most welcome.