Coinbase may have a track record of terrible support, but they also have a track record of doing the right thing (eventually), so I would think "whining on some Internet forum" (which happens to be one their CEO and employees browse, that's run by one of their investors) would in fact be a very efficient way of resolving the problem. Somebody else did the same thing yesterday and got a prompt response from Coinbase about rectifying the situation, so there's even precedent for this being a useful tool with them.