You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Karen Gonzalez here.

ASSISTANT: How may I help you today?

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 changing of my reservation?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Ok Karen, please wait for a minute.

USER: Sure, take your time.

ASSISTANT: Sorry Karen, there is no reservation found on your name in our database.

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

ASSISTANT: Thank you for approaching us.

USER: Welcome.