After spending $30-$40 on lunch boxes, the latest update came through and monsters wiped out nearly all my dwellers in what seemed like 30 seconds. I had no chance to defend myself and most of them have disappeared because of course I did t have enough money to revive 80-90 dwellers. I am not paying you that much money for the game to take back what I paid for. How can I get a refund?

By reporting an issue with your purchase in the Apple store.