You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I'm Sandra Lopez.

ASSISTANT: How can I assist you at this moment?

USER: I would like to change my reservation. Can you please help me with that?

ASSISTANT: Sure, I will help you with this.

USER: Thank you.

ASSISTANT: Please be on hold for a while, let me check your reservation status and get back to you with details.

USER: Sure, take your time.

ASSISTANT: Sandra Lopez, there is no active reservation found under your name in our database.

USER: Ok, no issues. Thank you for checking.

ASSISTANT: Thank you for utilising our service.

USER: You are welcome.