Boarded the train today and was booked to travel in AC-2 Tier. Ticket was in RAC, which got confirmed when the chart was prepared. To my shock and surprise, the coach designated as AC-2 Tier is in fact an AC-3 Tier coach. Spoke to the TTE and he says that he will issue a lower class certificate. But I prefer to travel in the class I had booked for. Please advice what can be done. Thanks!