Right now, the various GTA Online community forums are flooded with retellings of players' experiences with Rockstar support. Some of these are positive, while others... not so much. Basically, the first thing to do when you lose cash in GTA Online due to lag, glitches, or modders is to collect as much relevant screenshot evidence as possible and take it to the Support site for a refund — which usually is granted with a few hundred thousand $GTA bonus, for the inconvenience, you see.
On the other hand, screenshots can be cooked, meaning that Rockstar always follows up these claims. What many people do not realize or understand is that very,_very_often, Rockstar Support is utterly different from Rockstar. Considering how popular the developer's games are, much of the customer support work is outsourced.
While there are most certainly internal, actual Rockstar employees working on support, they are likely in the minority compared to CS contractors who do not have access to databases or game data. When refund requests are denied, they always happen with the same copy-paste corporate babble, as seen below:
Hello player name
Thank you for contacting Rockstar Support.
We understand your concern regarding missing GTA$. However, we have reviewed your account and was unable to verify this claim. We are sorry that we do not have the option to compensate until a verified loss is determined.
If you have further queries and concerns regarding your account, please kindly get back to us and we will assist you accordingly.
What this_doesn't_mean, is that the vast, greedy corporate machine that is Rockstar has decided to grind you, a mere mortal, in its vast gears oiled with microtransaction revenue like some infernal dystopian behemoth. What it_does_mean is that the person responding is a customer support contractor who quite simply doesn't have the authority to verify your claim or provide a refund, and will very likely get fired if they don't have a tickets resolved average of 30 per hour or something.
What you need to do in these cases is continue beating the bush until you get the fruit. There are several documented cases of players finally getting their refunds, so this is hardly a lost cause, however you might need to run a few rounds before it happens. Of course, your best bet is to stay far away from public lobbies so that the hack doesn't happen at all, but this may be a solution for those of you already hit.
Now, in case you thought things couldn't get any worse, we've got some more bad news. Players have reported (with screenshot evidence) that hackers now have the ability to add cash directly to your accounts remotely, without having to 'drop' money on you. On the one hand, this might not seem like that large an issue, seeing as getting money dropped on you won't get you banned anyway. However in light of recent events, it's reasonable to assume bigger crackdowns are in order.