You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Mary Martinez from Denver.

ASSISTANT: How can I assist you Mary?

USER: I want to do some changes in the existing reservation because my friends are not able to come on the those dates. Can you please help me in changing my reservation?

ASSISTANT: Sure, I'll definitely help you with that Mary. Please wait for a moment while I'll check your reservation status.

USER: Ok, thank you for your positive response.

ASSISTANT: Mary, I have searched for your reservation details in our database but there is no reservation found under your name to do changes in that.

USER: Oh! It's ok no problem. Thank you for your information.

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