You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you for the day?

USER: I am Carol Collins. Due to my health problem I want to change my reservation, can you please help me to change my reservation?

ASSISTANT: Ok, please hold on for a moment till I check with availability.

USER: Sure, take your own time.

ASSISTANT: I'm so sorry to inform you, but there is no active reservation in our data base.

USER: That's fine. Thank you for your service.

ASSISTANT: Thank you for consulting with our services. Have a great day ahead.