Thank you to @flavmartins for this article via http://www.winthecustomer.com :
1. Launching a premature, incomplete or untested product.
There is nothing that annoys customers more than being sold a bug-ridden or incomplete product that was advertised as ready for market. If you plan on doing an early release, make sure to limit the trial to a handful of “test customers” and let them know that the product is still in its testing trials.
2. Blaming customers for their own complaints.
Customers do not like being blamed for the problems they report even if they are the result of their own user errors. A frustrated customer can easily become an angry customer, so just helping them resolve their problem quickly is the best way to defuse these situations.
3. Being unresponsive or slow to respond to customers.
The longer customers wait the more frustrated customers will become and the harder they will be to deal with and keep happy. If you don’t acknowledge them at all, they will likely turn to the internet to voice their complaints and this could become very damaging to your brand.
4. Providing an unfriendly customer atmosphere or business experience.
Customers hate rude and unhelpful customer service representatives and love to complain about these experiences via social media.