You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. Which service you are looking for?

USER: Actually,my name is Thomas Carter and I want to change my existing reservation.

ASSISTANT: Yes sure. Could you help me with your name? Sorry, I did not find any reservation on your name.

USER: Oh! it's OK.

ASSISTANT: Sorry for inconvenience, have a nice day.

USER: Thank you.

ASSISTANT: Your are welcome.