You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello, how may I help you today?

USER: I want to change my existing reservation under the name of Joseph Garcia. Can you help me with this?

ASSISTANT: Sure, I will help you in this.

USER: Ok.

ASSISTANT: Please be on hold.

USER: Sure.

ASSISTANT: Sorry, we did not find any reservation in your name.

USER: Thanks for your quick response.

ASSISTANT: Thank you for opting our service.