You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello. How can I support you today?

USER: Can you please help me in changing my existing reservation in the name of Sandra Robinson?

ASSISTANT: Sure, I will help you.

USER: Thank you.

ASSISTANT: Could you please provide your name for checking the reservation?

USER: Already mentioned above.

ASSISTANT: Ok, please wait for a while.

USER: Sure, I will wait.

ASSISTANT: Sorry, no reservation found on your name in our data list.

USER: Not a problem, thank you.

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