You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: Myself Thomas Adams. I want to do some changes in my existing reservation because I did not get the concert tickets, so planning to travel on another date, can you please help me?

ASSISTANT: Nice to meet you, Thomas. Sorry Thomas, there is no reservation found on your name to change your reservation.

USER: It's ok. Thank you for the information.

ASSISTANT: You are welcome.