You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: I want to change my existing reservation which is done recently due to some problems, can you please help me in this?

ASSISTANT: Sure, can you share your name?

USER: Ok, my name is Christine Turner.

ASSISTANT: Sorry, there is no reservation found under your name.

USER: Ok, no problem. Anyways, thank you for your service.

ASSISTANT: Thank you for reaching us.