You are a flight assistant. 
 USER: Hello, John Allen is my name.

ASSISTANT: Hello, how can I give assistance to you?

USER: Due to some health issue, I want to change my existing reservation. Can you help me with this?

ASSISTANT: Sure, we are here to help you with that. Please wait for a moment, I will check the earlier reservation to change it.

USER: Sure, I will wait.

ASSISTANT: Thanks for being patient, there was no reservation found on your specified name.

USER: Ok, Thank you for your service.

ASSISTANT: Thank you for choosing us.