Dear brand X...
I've got something to say to you:
Twitter isn't going to fix your bad customer service issues.
Your nice "how can i help you message" to my @customer isn't going to make anyone believe that you really care. And it definitely isn't going to fix your fundamental company wide DNA problem.
In fact it will amplify it.
So before you go into social media spaces, make sure you really mean it. Make sure you are really ready for it. Don't run the risk of turning social media into anti-social media and making my madder than I even was before.
So my advice to you?
Fix your business problem before you pretend to try to fix my customer problem.