customer: Hello,. 
 agent: Hello, How can I assist you? 
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 agent: OK, Please wait for a moment I will check and get back to you. 
 customer: Sure. 
 agent: Thank you for waiting. We do not find an flight based on your details. 
 customer: OK, Thank you. 
 agent: Thank you for choosing us.
customer: I am Samuel and I want to change my existing reservation.