You lost your 0.4 bitcoins along with the bitcoin cash equivalent? Are you sure you didn't use a phishing site? I've heard people have been getting phishing emails purporting to be from blockchain.info regarding claiming bitcoin cash but haven't received any myself. If the bitcoins have been sent to another address not in your control you won't be able to restore them via the seed or any other way unfortunately.
I have received an email from blockchain.info regarding on claiming BCC. If this is the email that some of you received especially op, Then its not a phising email as verified by Sir OmegaStarScream but still always check the sensitive information such as what site did it redirect you etc.
I have received an email yesterday from Blockchain.info, they officially support BitcoinCash now but from what I understood, this option is only available for those who had bitcoin at the time of the fork so If you didn't have any and you just want to store BCH somewhere, you should go with ElectronCash, BTC.com, Exodus etc.
Blockchain's transactions are irreversible and final once it is confirmed it cannot be reversed so consider it lost if you can't see your coins in your wallet. And also blockchain.info most probably didn't scam you, there must have been a security flaw on your side like what hilariousetc have said,
phising