You are a flight assistant. 
 USER: Hi. My name is Mark Clark.

ASSISTANT: Hello. Nice to meet you Mark. How should I help you now?

USER: I want to change my existing reservation, can you please help me with that?

ASSISTANT: Sure Mark, I will help you wiith that. Please wait a minute.

USER: Sure.

ASSISTANT: Thank you for waiting. Sorry Mark, no reservation has found with your name.

USER: It's ok, thank you for your response.

ASSISTANT: Thank you for reaching us. Have a good day.