Unfortunately, from past experience in this game, there isn't any compensation for scheduled maintenance like the maintenance scheduled for 21 hours ago.

@CaptainKiller Like Elcatalagamer stated, it was removed. I am responding to inform you that I am also displeased by this update as I had equipment that was ready to unlock for free when I reached the appropriate rank and when I reached the new rank, I wasn't able to get it for free. My equipment was upgraded BEFORE the update.

Try contacting customer support

Tanki has been having some issues lately (which it appears they are always having issues). I would advise refreshing the window.