My neighbor has a handicap signe on the street but he does not have the proper plates to the permit,?

Let me explain, this family has 3 huge SUV and they have a Sign of handicap in the street. However NONE of those vans has the handicap license plate and the only thing they display is the permit hanging on the windshield. They taking advantage of this situation and park the other 2 vans on the front and back of the handicap space and not using the one that is reserved for them, leaving the rest of the neighbors with out a parking space because obviously we can not park on the handicap space. Finding a parking space in my neighbor is like winning the lotto and we really need those spaces she is misusing. Is there any way to find out if this family is using a fraudulent permit (remember this permit they got it is only displayed int he windshield and not as a license plate)? Where can I report this abusive behavior? Several neighbors are very upset because of this and personally I need to know if I can do something Thanks.