LOST LUGGAGE

I flew Northwest from DTW to RDU, and when I arrived I realized that my luggage was not on the flight with me, I reported it to the luggage center and was told that it will be on the next flight. 36 hours later I have not recieved any information on my luggage, when I called the 800 number one agent called Kate told me there is nothing she can do about it and hanged up! Another agent told me "You are not the only one with a missing luggage you know so chill out" I have been misled so many times by the staff of Northwest I start to question if this company understand that the missing bag is my property and I am entitled to it, the content is mine and I paid for the airline ticket and therefore should have gotten off the plane with my bag; No! but rather they get upset and tell you inconsistent stories and when you question something they hang up. I am done with Northwest/KLM never again will I fly their plane but I still want my luggage.