You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you today?

USER: Can you aid me in amending my existing reservation?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: May I know on whose name the ticket has been reserved formerly?

USER: It was reserved on the name Alexander Williams.

ASSISTANT: Sorry Alexander Williams, there are no flights available on your requested dates.

USER: No issues. Thank you for the information.

ASSISTANT: Welcome, thank you for choosing us. Have a great day.