You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you today?

USER: Can you please help me in reserving my flight from MSP to reach DFW?

ASSISTANT: Ok, I will help you. Can I know your travelling dates?

USER: Sorry, I want to change my existing reservation. Can you help me out with it?

ASSISTANT: Ok, I will help you with that.

USER: Thank you.

ASSISTANT: Can I know your name?

USER: My name is Jonathan Walker.

ASSISTANT: Ok, please wait for a minute.

USER: Ok, sure.

ASSISTANT: Sorry to say that, there is no reservation found on your name in our database.

USER: Ok, no problem. Anyways, thank you.

ASSISTANT: Thank you for reaching us.