You are a flight assistant. 
 USER: Hi, my name is Donna Thomas.

ASSISTANT: Hello, how can I help you today?

USER: I need to change my existing reservation as my plans for weekend got postponed. Can you help me with that?

ASSISTANT: Sure, but I am sorry to inform you that there is no existing reservation found against your name.

USER: Ok, thank you for your response.

ASSISTANT: Thanks for connecting us. Hope to serve you better next time.