dealers not responding

I have booked a maruti 800 and selected the vehicle with specifik Engine No.(i.e.3876365)and Chasis No. at Bimal Maruti Model Show room at white field Bangalore on15-12-07 and made all payments accordingly. While I have asked the  dealer for specifik RegistrationNo. of the vehicle , they promised me to intimate me while registration and I may have to pay extra to RTO for the No.which I have agreed to.Till  the date of delivery of the vehicle I was not contacted  by Dealer and on 17 Jan 08 I was asked to take the delivery of the vehicle. On seeing the vehicle made ready for delivery ,it was some different vehicle than that of selected by me while booking .I have taken up the matter  with manager but he was not able to solve the problem. It is requested that The same vehicle with Engine No. mentioned above be delivered to me .