You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: Donald Martinez here, can you help me for changing an existing reservation?

ASSISTANT: Sure, I am here to help you. Please wait for a minute to check your details.

USER: Ok, I will wait for your response.

ASSISTANT: Sorry, there is no reservation found on your name in my database.

USER: Oh! It's ok, no problem.

ASSISTANT: Would you like to know anything else?

USER: No, thank you for your services.

ASSISTANT: Thank you for reaching us, have a nice day.