The price wasn’t raised for Ukraine....the billions in vast subsidies were cut and price raised to what other European countries pay. This puts Ukraine in position for renewed negotiations.....they will have no choice but to meet with Russia...which is what Putin wants.
This pressure is exactly as the EU and US do as well, when they want to force their agendas. Ukraine is in the squeeze now to get that from all players.
Well... more along the lines of 'we've been selling this gas duty free for a while, in exchange for that port in Crimea, but since you no longer provide that service, we're no longer waiving the duty fees. Oh, and give us 2.2 billion for the gas you've already received that you still owe us.'