I think you may be confusing XP and credits.
XP are awarded for playing and help level you up - Credits are earning via offer, paying, or winning credits and can be used to upgrade your equipment )better equipment is available at the higher levels).
As you tiered up from hack you would have gained some credits, but tiering up is a result of improving at the game, not your level.
If you want credits, go to the Get Credits at the top of the page and try your luck in Earn Free Credits. For players outside of the US or UK, good luck as it is usually slim pickings. Or open your wallet - less hassle IMHO.