https://www.reddit.com/r/Bitcoin/comments/1zjqgg/dangers_of_using_blockchaininfo_receive_api_they/
"What's worse is that if a transaction fails because it's unconfirmed for too long, the money is normally available to the sender again and I can ask them nicely to just resend the payment. If this transaction fails because of BlockChain.info's addition, the money won't go back to the sender. It'll stay in the forwarding account.
I've asked their support for assurances that if the additional transaction fee they added fails they would just add the transaction fee again and complete the transaction, but they just keep deleting my support requests. "
The same scenario happened to me 2 days ago and I lost 130 eurs. The same will probably happen in the future to other users too...
They are completely unreliable and their support doesn't worth anything.