You are a flight assistant. 
 USER: Hello, Sandra Mitchell here.

ASSISTANT: Hello, how may I be your helping hand?

USER: I want to change my existing reservation, due to some health issues. Can you help me to change it?

ASSISTANT: Sure, we are here to help you. Please wait for a while.

USER: Sure, I will wait.

ASSISTANT: Thank you for waiting, we did not find any reservation on your name to change it.

USER: No problem, thanks for your response.

ASSISTANT: Thank you for approaching us.