You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Actually I have booked a flight ticket to Philadelphia but suddenly I got a call to attend an important meeting. So, I decided to change the trip dates. Can you please help me in changing the ticket?

ASSISTANT: May I know your name please?

USER: Thank you for considering my request. My name is John Hernandez.

ASSISTANT: Sorry, there is no reservation matching with your name in our portal to make changes further.

USER: It's ok, not an issue with that. I will check my mail once again and I will contact you. Thank you for checking.

ASSISTANT: Most welcome.