I bought Gall two weeks ago (I think that was the timeframe) he worked for a bit, but the next time I played (last week) he was no longer available and my money was still gone. 
Can anything be done?
This might be an obvious question from me, but are you queuing with a Cho player? You canât play Gall alone, and he is greyed out in the hero menu until a player also selects Cho, then you both can press Ready.
(The other player does not need to own Cho to play with you, as long as you own Gall)
When you go to âpurchase historyâ in your Account Settings on battle.net it will show all the gold & real money purchases youâve made on your account. If you canât find Gall itâs also possible you played him on free rotation. Both Cho and Gall have been on free rotation quite a few times.
If that is not the case, it could also be you played with someone who owns Cho while you hadnât unlocked Gall.
It is true I played with someone owning Cho and Gall, though he was not on rotation. However, I also bought him, but now my purchase history says I bought Dehaka. (probably the last character I had selected) I see other bug reports about the same thing, so I suspect it is a real bug.
If there is no gold or gem purchase history of Cho or Gall on your battlenet profile, you may have played with someone who has unlocked one of them.
It is possible to play Cho / Gall without owning either one or without them being on rotation (as long as the other player has one of them).