Capitalism and democracy are opposite sides of the same coin. They both introduce the inefficiency of choice in order to counteract the centralisation of power which can be misused to give benefit to the folk at the top by charging more or giving worse service to the customers/citizens at the bottom.
The problem with both is that choice here doesn't mean multiple candidates - it means citizens having the ability to take their business (or their votes) to someone else. This requires:
* There must be at least one candidate (otherwise it's just despotism / a monopoly)
* There must be at least one candidate which is different (otherwise it's just a one-party state / a cartel)
* It must be possible to choose the other candidate (otherwise it's vote rigging / anti-competitive behaviour)
* If all else fails, it must be possible for you to stand as an independent and win.
The problem is that banks and pension companies all act the same, don't have customer's interests at heart, it's impossible for you to set up your own bank/pension company and so all of the capitalist benefits of consumer protection and appropriate rewards leading to good management behaviours aren't happening.
The problem voters in the UK and the US are increasingly seeing is exactly the same. Sure political parties are great at tearing each other apart, but no matter how much gets said on the issue, the things voters would like to change never do get changed (like immigration, the EU, bailing out bankers, foreign wars, police powers, the political-media machine, lobbying and corporate greed to name but a few). You also can't form your own party in the US and ever expect to win, and in the UK you can't ever form a government without a majority in parliament, and you can't ever form a majority in parliament by yourself, no matter how popular you might be across the country.
So anyway, my point is that I absolutely agree with Maddus that taking my business elsewhere (and W3bbo's point that you can just vote differently) should work. The point I want you to consider is that it doesn't work precisely because the west isn't even close to a capitalist/democratic ideal (and letting the system work itself out has clearly not worked because we got to where we are now precisely by letting the system work itself out).