Changing bus services without prior announcement leading to customer failing to board the right bus

Location/place: Chennai

Name of company/service: Kallada Travels

I had booked a bus ticket for travel from Chennai to Coimbatore on 14-03-2013, 10 PM. The ticket# TF4C26644335. The bus service# as indicated in the ticket was C21. During the time of boarding, they sent a bus with service# C11. When I checked with them, they said that the bus I am supposed to board will be arriving shortly. I waited for 1 whole hour, but the bus never came. When I contacted the Kallada travels office, they informed me that the bus service# has changed to C11 and that not boarding that bus was my fault. They never informed me of the change prior to the boarding time. They also refused to refund my travel expense.