I wouldnt hold the police department liable for trespassing, but i would call them up and let them know ur not going to take it again or forget it happened. They seem to want your cooperation, so just tell them your happy to comply within your rights, and next time they decide to ignore your rights they will not get any cooperation. It goes both ways though they make it seem onesided on the whole cooperation part, if your under the impression they are not doing there job, then really you would feel safer not telling them anything, i would write up a letter send it to your mayor sign it date it copy it and save it as a record that they did enter your house unlawfully, this way if something comes up in the future you have a reason to make there lives harder.