Try contacting them on twitter, they seem to be more active there: https://twitter.com/AskBlockchain

You can confirm it's legit by checking it is linked on their official twitter's profile description: https://twitter.com/blockchain

And please, be extremely careful with this. Always triple check you are replying and reading from their real twitter account. Scammers may try to impersonate them and DM you, or reply to you with "AskBlockchein" or similar, asking for confidential data. Do not trust anyone, and be extra paranoid.