Lenovo Ideapad Y[protected]q — Registration

I have purchased this laptop from House of laptops, Tilak road, pune on 28th Aug '08. I faced one display problem last week. When i went to service center, they called Delhi service center. They asked my serial number and said the laptop is registered on some other's name and not responded to me. Then the dealer logged complaint in service center and got mu laptop serviced on that other name. But the laptop is still not registered in my name. The repair receipt has Mangesh Kumbhar as owner of laptop. I think the dealer had sold this laptop to him and sold it again to me b'coz it may be having some problem. On the invoice which i'm having, the serial number is of motherboard and not of laptop. Should i file case on dealer? Please help. The laptop still in warranty period.