You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Lisa Miller here.

ASSISTANT: How may I help you out now?

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

ASSISTANT: Sure, I am glad to help you in that ticket modification.

USER: Thank you.

ASSISTANT: Please give me a moment to check it.

USER: Ok, take your time.

ASSISTANT: There is no reservation found for the user name in our previous booking list.

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

ASSISTANT: You are welcome and thank you for reaching us.