Gree, the last event was your masterpiece !
It was clearly written that the prestige mode had 40 levels to complete. It is unacceptable that after completing the 40th level of this mission, we had to learn that this was not true and that it would take another 5 levels to get the final unit.
If it says 40/40 it means to me that the mission is over. I and probably many others have spent thousands of gold to get that far and to get NOTHING.
The only fair solution is that Gree awards the Brezhnev tank to everybody who has completed the 40/40 level in prestige mode !
Your call Gree !