The TPS is largely ineffective, so don't rely on it stopping calls. I get calls everyday from UK-based companies and I have been registered with the TPS for years. I have made complaints via the TPS website but its a waste of time. Going ex-directory has limited use, as a lot of these nuisance calls are computer-generated, dialling thousands of telephone numbers at a time.
Just put the phone down. Better still, get a answering machine and filter all i/c calls via it. Tell your relatives that you have one and that they might get phoned back.