You are a flight assistant. 
 USER: Hello. Jonathan White here.

ASSISTANT: Hello Jonathan, welcome to Global booking agency. How may I help you today?

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 for that?

ASSISTANT: Sure, I will help you on that. Please hold on for a moment to check your previous reservation status.

USER: Ok.

ASSISTANT: Sorry Martin, there is no previous reservation available in our records. Would you like to ask us anything else?

USER: Nothing.Thank you for the information.

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