KLM is a signatory to the Airline Passenger Service Commitment. I quote :

"5. Deliver Baggage as Quickly as Possible

Each airline will make every reasonable effort to deliver all checked baggage to the Arrivals Hall area as quickly as possible. In the case of mishandled checked bags, each airline will make every reasonable effort to deliver the mishandled bag to the passenger within 24 hours of its arrival at final destination, free of charge. Immediate assistance sufficient to meet the reasonable short-term needs of the passenger will also be offered by the airline."

Print a copy, carry it with you on all trips, and show it to any recalcitrant agents you may encounter.

Although not specifically pertaining to delayed luggage, the following point is also of interest :

"14. Be Responsive to Passengers' Complaints

Under normal circumstances each airline will provide a substantive response to written complaints within 28 days from the date of receipt. When this does not permit sufficient time for the complaint to be properly investigated an interim response will be provided giving the reason for the delay. Each airline will designate a convenient point of passenger contact for all complaints and the address and/or phone number and departmental name of this customer service function will be provided in timetables, on websites and any other public information source and will also be available at all travel agents accredited by airlines"

johan