You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you today?

USER: I want to change my reservation due to health problem, can you help me?

ASSISTANT: Sure, we are here to help you. On whose name, the reservation has been made?

USER: Please check the reservation under the name of Timothy Martin.

ASSISTANT: Please wait for a while, I will check the reservation list and get back to you.

USER: Sure.

ASSISTANT: Thanks for your time, we are sorry to inform you that there is no active reservation found in your name to change.

USER: No problem, thanks for checking.

ASSISTANT: Thank you for opting us, we will try to serve you for the next time.