I just played game and at new login I had balance of 87 but at last login I had 387, so first I thought I lost them at nowhere, then I thinked about mybee I spend them accidently at something, but I cant find my purchase history, so now I think I just lost them
Hello, crystals can't disappear for no reason, they can be only spent in the game. Most likely it was Instant Callback item, which costs exactly 300 Crystals. More info about Crystals and how can you spend them here.