when I was leaving pc, I had 190 key credit. Now I came back. Have 183 credit + arma 3 for 14.5 and space engineers games for 4 credits been sold. So any solution ?

Well, probably nothing is wrong.

To be fair to us you should compare your ledger to one from a prior time if you think there is any "calculation mistake". If you do not see any weird entry (like some transaction that gives you negative credit), then the chance that there is any "math" problem is slim.