Try to follow it up on their social media sites particularly on facebook as they have been tagged as "Very responsive to messages" and "Typically replies instantly" although I don't know if their replies can actually be helpful as you might only get automatic replies.
Facebook: https://www.facebook.com/xapoapp
Twitter: https://twitter.com/xapo
*Try to ask nicely and make it concise, avoid making it into a long essay and as much as possible include some proofs e.g. screenshots etc.
In xapo's case, they have an access afaik but the users are not allowed to access it so if they deemed that you've violated their whatever TOS, they can block your account and you who doesn't have your private keys can only beg xapo.
Oh hey that's pretty shady imo. Staffs shouldn't have any access to your wallet. If someone claiming to be a staff of any wallet says the exact same thing, It meant "give your private keys to us and we will check if you really have funds so we can transfer it to our wallet"