When you contact Kucoin, do not accept the answer that "assets can not be retrieved if they are not sent to the correct network". Tell them that you are aware that an Ethereum network address is accessible on every network with ease. It is only a matter of exporting the private key and importing it to the correct network. Badger them profusely until you get your funds back. Do not accept that they are lost.

Good luck, and next time please be more careful.