Western Union admitted to aiding wire fraud and was charged a $586M fine! The allowed all sorts of scams to be facilitated through their payment service - think Dark Net stuff.
But the worst of it is that WU knew about the fraud and didn't do anything to stop it.
The fine was a very huge amount and aside from that the credibility of Western Union was tainted. Western Union was having problems with bitcoin and that is why they offer services to dark net activities. Its my opinion but possibly Western Union are having problem with their sales lowering and tried to raise it up by moving on to the dark side.