As I understand Air Deccan is a no frills carrier and the lowest fare they offer to passengers are abysmally low, lower than Rs.100 and as such one can not expect class service on board or while on ground. The fare may be higher towards the date of your travel as all budget carriers price their products in such a way. This airline do not give seat number to passengers making you to run and board the plane as soon as departure announcements are made. Otherwise you may end up sitting in a middle seat. No free items including water is given on board and you are forced to buy these if you require them.
All over the world all budget carriers are functioning like this and this airline is no exception. So it is always better not to expect anything when one buys the ticket. The fare also include the taxes or surcharges which all other airlines are also charging the customer.
Also try to read the conditions written on the ticket before you start the journey.
It is lack of computerisation of counters in all stations, may be one of the reasons for not assigning seat numbers. Also, when a particular flights pass through intermediate stations, both the stations should be computerised to give seat numbers to passengers in an orderly manner. I also understand if requested the staff gives front row seats for senior citizens, mothers with infants etc.
They are doing a good service by connecting hitherto unconnected places by air, utilising small aircrafts. It is a fact that when so many people gather and travel complaints are supposed to arise and the management should find a way to address passenger complaints.
It is also to be considered that they have given jobs to thousands of people. Their last minute fares are not cheaper but costly.
Have a nice flight.