You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Alexander Thomas here.

ASSISTANT: How can I help you today?

USER: Suddenly my friends changed the trip plan.So I want to change my reservation. Can you please help me for that?

ASSISTANT: Sure, I can help you with that. Please allow me a moment to check for the previous reservation.

USER: Ok.

ASSISTANT: Your patience is greatly appreciated. Alexander, I see that there is no reservation found under your name.

USER: Ok, thank you for the information.

ASSISTANT: You are welcome. Thank you for contacting us.