You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am William Thomas.

ASSISTANT: How may I assist you today?

USER: I want to change my existing reservation due to heavy rainfall, can you please help me with that?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Sorry to inform you that there is no active reservation found on your given name.

USER: Not an issue, thank you.

ASSISTANT: Thanks for contacting us.