I know it *69 but it don't work wit private call... how do I unblock them?

You can't. If the caller initiates "no data sent" by selecting block or pays the premium for private caller feature, then no data is sent. That's that.

Try this site:
harassingcalls.com: Identify ALL of your calls (http://www.harassingcalls.com/)
Looks a little expensive.

*69 is typically a call back feature rather than blocking or unblocking. It will give you the number of the last incoming call.

You cannot unblock a private call if the caller wants their number blocked.

You can get Automatic Number Identification (ANI) hardware to read from the actual routing information of the call, instead of the caller ID information provided by the phone company. It's basically like a phone trace, but I believe it's pretty expensive stuff.

Automatic number identification - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Automatic_number_identification)

ANI is also a number you call, and an automated voice will tell you the line you are on.
Very helpful, to make sure you are connecting to the correct line.