If you have suifficient evidences you can still follow it up and ask about the status of your refunds to the blockchain.info customer service. After all, it's their grave mistake that makes you losing so many BTC and NOT your fault. They're responsible for this, rejecting your request of refund by nonsense reason such as "long time has passed" doesn't make sense at all, well unless they really delete the entire logs or data back then.
I guess that there's no other way to recover your bitcoin once it lost and moved to another address that you don't have access to. The only way is to enforce your right of having the refund from blockchain.info.