1. At the time of booking, I selected Seat No. 7 (in middle of bus) whereas at the time of boarding I was offered the last seat in the bus, which was very un-comfortable. There is no meaning in such a case to select and book a specific seat at the time of booking.
2. At the time of booking, the departure time of bus was shown to be 08:30 pm while the bus actually departed at 09:50 pm.
3. Based on above two points, it seems that the bus was changed at their own sweet will and hence there is no meaning of any benefit of online bus booking.
4. Probably my actually booked seat was offered on a higher price to someone else as it was already occupied. In such a case I was left with two options: (a) arguments and create an un-necessary scene and probably get de-boarded from bus (b) surrender silently. I opted for the second option helplessly.