You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Jack Walker here.

ASSISTANT: How may I assist you?

USER: Due to sudden change in my planned dates of journey, I would like to change my reservation. Can you please help me out with that?

ASSISTANT: Sure, please wait for a while, I will revert you back with the status of your reservation.

USER: Sure, take your time.

ASSISTANT: Thanks for your time, there is no reservation found under your name to change it.

USER: Oh! I think the ticket was not booked properly while I am booking. Anyway, thank you for the information.

ASSISTANT: Ok, thanks for choosing us.