You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I want to change my existing reservation, can you please help me in that?

ASSISTANT: Sure, can you provide your name?

USER: My name is Ruth Roberts.

ASSISTANT: Sorry, we did not found any reservation under your name.

USER: Ok, that's not a problem. Thanks for your information.

ASSISTANT: Thank you for reaching us.