You have the original file with you OR with Registration office, Both are possible, ask the seller, He has the file OR is it left with the Registration Office, ok ?
For CPLC, I can give you the contact Number:
021-5682222
021-5683333
Remember these numbers are to verify that the car is not stolen, You tell the Registration Number, they will ask for Chassis/Engine Number and will tell you that the car is ok or Not.