Fair enough - but Russians have played this very well, actually. What they did is the forced the EU (Germans, to be exact) to do their dirty work for them. I can assure you Germany's screaming bloody murder at the Ukrainians. And you're incorrect - only 25% of EU exports go through Ukraine. Russians said, ok, we're turning the gas back up, but if there's a drop in gas, means Ukrainans are siphoning off. They'll even put the EU observers in the pump stations to show the EU they're pumping, but if gas doesn't arrive in EU, means Ukraine's taking the gas. Puts the Ukraine between the rock and the hard place. Try explaining the Germans where the gas went.
As far as I'm concerned, Russians are welcome to give discounts to whom they like. If they like Belarus, let them sell gas to them at a loss. I don't care. But I can't support Ukraine moaning/groaning about being charged market prices. I can guarantee you Ukraine's independence from Russia rates far below Germany's (and EU's) need for the natural gas on their list of priorities.