generate response: I apologize, I forgot to mention that I'll be needing 6 tickets, not just 1.. Intent: book_train. Slots: train-bookpeople=6, train-day=monday, train-departure=bishops stortford, train-destination=cambridge, train-leaveat=13:15
Response: Okay! I've changed your reservation for 6 tickets rather than one. The reference number is now QHYYACDV .