Make sure that your windows are really shut tight and if you have a sunroof, make sure that is shut correctly. Then what I do is I sit in the car and have someone spray the car with a garden hose near the area where the carpets get wet, to find the location of the leak. If you are getting water in your car, it could effect anything electrical, like the door locks and remote. Can't say what it will cost, until some one determines what is wrong with the remote system. Here is a list of shops.
http://repairpal.com/directory?address=20737&car_brand_na...