Rember whe he had Andy beaten half to death for sleeping with his wife/beard that he never loved or wasn't attracted to. considering he has this kind of contacts and power why the hell has he never sent them for Robert considering the damage he's done to his family?

Because it's not convenient to the plot and would end Robert's interference in his family and therefore put an end to the storyline. They need Robert to interfere in his family to create conflict. I know, it's pretty contrived but that's the way it goes on soaps.

Don't get me wrong though, I would love to see gold-digger Robert get a good beatdown. I'm baffled at how the writers seem to be suddenly portraying him now as some sort of good guy/hero of the Sugden family...

God, me too.

I don't know why Don Lawrence Whiteoni doesn't hire someone to whack him, but as you've said, he only goes Gangsta when the plot requires.