You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

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

ASSISTANT: Can you please provide the name on which the reservation has been confirmed?

USER: Sure, my name is Mary Scott.

ASSISTANT: Sorry, there are no reservation found by the name that you have provided.

USER: No problem, thank you so much.

ASSISTANT: Have a nice day and take care.