You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, what can I do for you?

USER: Gary Garcia here, due to sudden work I need to change my reservation. Can you please help me with it?>.

ASSISTANT: Ok, please wait. I will check your reservation and revert to you.

USER: OK.

ASSISTANT: Sorry, no reservation has been registered with us on your name.

USER: Not an issue, thank you.

ASSISTANT: Thanks for reaching us, have a nice day.