You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you?

USER: I want to change my existing reservation which is done recently due to some problems, can you please help me?

ASSISTANT: Sure, may I know your name please to check the reservation status?

USER: Ok, my name is Donna Adams.

ASSISTANT: Donna, there is no reservation found with your details.

USER: Ok, that's fine. Thank you for your service.

ASSISTANT: Thank you for reaching us.