10000 Rs more than MRP

Location/place: chennai

Name of company/service: sharp AC through M/s Girias Investment pvt Limited

I have purchase one split inverter AC, AH-XP13LV(1.1 TON) on 06th June 2013 from M/s Girias Investment pvt Limited , Virugambakkam , Chennai-92. Next day the AC has been delivered at my house. I have observed that the MRP given on the AC packing is only Rs. 12867 ( Inclusive of all taxes). This is the price given on both packing (indoor and outdoor unit). If taking both price separately also, the total cost comes only Rs. 25734/-(Inclusive of all taxes). The price in the bill is Rs. 35600/- . Kindly clarify why this price difference more than 10000 rupees /.