You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: Due to change in my plans to visit Dallas trip, I would like to change my existing reservation. Can you help me with this?

ASSISTANT: Sure, may I know your good name please?

USER: My name is Ruth Turner.

ASSISTANT: Ruth, there is no reservation found under your name in our database.

USER: Ok, not an issue. May be something went wrong while booking the ticket.

ASSISTANT: Yes, may be.

USER: Anyways, thank you for your help.

ASSISTANT: Thank you for choosing us.