You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am very happy to change my existing reservation because my examination was postponed, now I have much time to prepare for the exam.So please help me in modifying my recent reservation.

ASSISTANT: Sure, I will help you in modifying the ticket. Please, provide me your name?

USER: Please check with the name of Alexander Perez.

ASSISTANT: Sorry Perez, no reservation found on your name.

USER: It's ok, not a issues.

ASSISTANT: Thank you for contacting us.

USER: Thanks for your checking.

ASSISTANT: Welcome.