You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, may I know your name please?

USER: I just want to change an existing reservation due to my exams got post pone, can you please check the reservation with the name John Martinez?

ASSISTANT: Can you please wait for a moment, I will check with your reservation.

USER: Sure.

ASSISTANT: Sorry, we did not find any reservation registered with us on your name.

USER: Not an issue, thanks for your information.

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