You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: Christopher Lewis here. Due to sudden change in my planned date of trip, I would like to change my reservation. Can you please help me out with changing of my reservation?

ASSISTANT: Sure, I can help you with that. Please wait a moment I will check your details and proceed further.

USER: Sure, take your time to check.

ASSISTANT: Sorry to say, I did not find any details regarding your reservation in my website.

USER: Oh! I think the ticket was not booked properly while I am booking.

ASSISTANT: Thank you for choosing us, have a nice day.

USER: Anyways, thank you for the information.