The easiest way for them to solve your problems is to follow them up on their twitter page and always be posting your issues on their post as comment with this your problem will be solved so easier. Also comment why are they changing you such whooping amount for just to make refund since you withdraw to the wrong address.
Always follow them up in all their tweet to post your issues over there.
Cases like this are very sensitive and as such not good for publicity because it would attract Scammers to your inbox and OP had the experience for making it public via their social media handles.
At first, the fee charged by kucoin is way too high than expected. I believe this is amongst the major reasons bothering OP. I understand that the process involved is somewhat inconveniencing for both the kucoin exchange and their staff but I think there should should always be considerations when dealing with customers.
Nevertheless, the money to be recovered is another factor to determine if the process should go on or not. For OP to have approved of the transaction, then the asset is of good value but however, I think that is the reason why the kucoin exchange took advantage of it to demand such an amount for processing of the withdrawal because they know OP would not allow his asset stucked up in the exchange without him accessing it so they acted smart by demanding such an amount because OP would give in to the payment. This is possibly the case of exploitation by the exchange of I am not mistaken.