What about blocking their numbers and block all the blocked -'private' numbers coming in?
Program it s called 'blackballer' you can get it off the nokia website for all OS 3 soft which means N70 onwards......
When call comes in u receive just a small beep and u can create lists who s ignored for 1 day who s for all the time
And messages sent by ignored numbers end up on blackballer too they dont go to your inbox....
Loads of peacefull times it gave to me
I can check for something similar for other phones too.
I think blackballer is originally made by killermobile dot something.....