Actually there is! I have only just found it today. Related to murders of Colombian trade unionists.
There probably should be a bigger one since I seem to hear a lot of stuff about how they try to foist their products onto school kids, etc. Personally I don't really believe that consumers have the power to govern corporate policy, I think that's a bit of a myth. Its all very well in theory but most consumers are restricted by things like poverty, addiction, lack of education and misunderstandings based on biased advertising campaigns, lack of time and lack of genuine choice in the markets. On top of this a lot of companies don't sell to consumers directly - they sell to other companies or government departments which in theory we should still be able to influence with our voting policy and through secondary level consumer influence. In practice however, corporates are doing everything they can to make this as difficult as possible (err like murdering trade unionists for one thing).
However there are times when we can do something. Maybe not solve the problem but consumer pressure has clearly affected policy at McDonalds. Coke - with its 100% reliance on consumer buyers, should be vulnerable too. I shall stop drinking Coke and Coke-made brands today.
For those who would like to do the same but can't live without a fizzy caffeinated drink I recommend switching to Irn Bru, which is independently produced within the UK - where trade unionist murders are fairly rare and pollution controls are a little tighter. And is produced under a strict environmental policy, viewable on their website.