Finally, so many companies do customer support via Twitter and ask folks to DM them the details and you're limited to describing what help you need in 140-characters.
But the enforced brevity (in the form of a 140-character limit) is probably precisely why this works. Otherwise the same companies would be doing support over email.
Actually, people go onto Twitter to complain because it's a very public forum. It's a terrible shame that in order to get some service now-a-days you have to basically publicly shame them or find some way of getting their CEO's private email.
It's also easier to find a company's twitter handle than the correct support email address (if they even expose one without requiring you to sign into an account or fill out a form).