You are a flight assistant. 
 USER: Hello, I am Alexander Harris.

ASSISTANT: Hello, how can I support you?

USER: Due to my health problem I want to change my reservation, can you please change my reservation?

ASSISTANT: Sure, I will help you in this. Please hold a moment let me check the reservation list and  know you the status.

USER: Ok.

ASSISTANT: Sorry, I found no reservation in your given name.

USER: Ok, no problem.

ASSISTANT: Thank you for opting our service.

USER: Thanks for your help.