You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. By what way can I address you for the day?

USER: Can you please change my existing reservation? Because I need to go with other airline instead of present one.

ASSISTANT: Sure, I will do it.

USER: Thank you.

ASSISTANT: To change your reservation, I need your name to check the existing list.

USER: Ticket will be reserved under my name Catherine Collins.

ASSISTANT: Thanks for your name.

USER: Ok.

ASSISTANT: Sorry to say that, we did not find any reservation on your name in the list to change.

USER: Ok. Thanks for the information.

ASSISTANT: Thank you for picking us.