[{'role': 'USR', 'utterance': 'Could I have my bill, please?'}
 {'role': 'SYS', 'utterance': 'Certainly, sir.'}
 {'role': 'USR', 'utterance': "I'm afraid there's been a mistake."}
 {'role': 'SYS', 'utterance': "I'm sorry, sir. What seems to be the trouble?"}
 {'role': 'USR', 'utterance': 'I believe you have charged me twice for the same thing. Look, the figure of 6. 5 dollar appears here, then again here.'}]
{'role': 'SYS', 'utterance': "I'll just go and check it for you, sir."}