What happens if I sendBitcoin Cash to a Bitcoin address?
At this time, Coinbase has already credited accounts who received any BCH at their existing BTC addresses. Going forward, we cannot guarantee that funds will be properly credited when one asset is sent to the address of a different asset. Please make sure that you only send funds to the specific deposit address displayed in your Coinbase account for the asset you are sending. You can view a list of these addresses, or create a new one, by visiting this page.
If Coinbase already have this, I think there is nothing you can do.
Coinbase and other centralized wallets and exchanges are so wise, if the amount is high, you might (I am not certain because it is Coinbase that will give you most valid information about this) be given back your coin, especially if they know that the amount is high to the extent the victim can file a law suit against them (Coinbase).
For low amount, the coin is gone. (I hope someone can post the minimum amount that can be sent before Coinbase can refund the person. I think I have seen that before in the past).
To have full control, use a reputable noncustododial wallet.
