so obviously this isn't the usual problem where all my credits disappeared, although i did try downloading and running GluCreditRestore, to no avail.
i rated CKZ2 on google play (5 stars, cos the game is awesome, though somewhat frustrating) hoping to earn 5 credits. got back to the game and my credits had dropped from 10 down to 1. never received the 5 new. i def didn't buy anything cos what the hell can you buy with 9 credits???
other than that, thanks for a great time waster (that may sound sarcastic, but isn't meant as such)