Changing your PSN password, which you should have done as soon as your console went missing, will prevent the person that has your console from doing anything that matters with your account. Deactivating any content, except for game content, from a PS3 requires that you have access to the PS3. As you do not, then you must contact Playstation customer support by phone (800-345-SONY) or live chat to get the deactivation done. If the police won't investigate the case, then Sony will not do anything to recovery your stolen console. Sony relies on police involvement to establish that the console is, in fact, yours. There is no other way for Sony to know that.