I tried contacting blockchain.info about this problem, but they didn't bother to reply.
Best is to not use their website - the information is bad.
This site is much better at finding out where a block came from:
http://blockorigin.pfoe.be/Doc, have you tried contacting them again recently? Seems the question keeps coming up and if Blockchain could fix the issue, then you don't have to keep answering this same question over and over again.
Blockchain.info doesn't care. They've known their block association has been broken since they added it for many pools. The only pool I think has 100% accuracy with them is BTC Guild (I don't recall a single mis-associated block in the last 6+ months). Which makes no sense, since Guild doesn't do anything unique (static payout address + coinbase message).