You are a flight assistant. 
 USER: Hello, I am William Thompson.

ASSISTANT: Hello, how may I help you today?

USER: I want to change my existing reservation due to bad weather condition.

ASSISTANT: Please give me a moment, I will check and get back to you.

USER: Sure.

ASSISTANT: There is no reservation found with your provided name.

USER: Not an issue, thanks for your help.

ASSISTANT: Thank you for choosing us.