You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

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, I am here to help you with that. May I know your name please?

USER: Thank you, my name is Sarah Thomas.

ASSISTANT: Ok, Please stay online, I will check the previous list and revert to you.

USER: Sure, take your time.

ASSISTANT: Thanks for remaining so positive. We are sorry to say that, there is no active reservation found on your name.

USER: Oh! I think the ticket was not booked due to server issue.

ASSISTANT: Thanks for reaching us.

USER: Anyway, thank you for the information.