“The truth will set you free, but first it will piss you off.”
~ Gloria Steinem
The issue is so severe that angry customers have made it a point to "Like" the page of the brand and comment on posts that are unrelated to customer service to vent out their frustration.
The irony of the situation is that there are brands that spend money on getting fans and then find themselves in a spot when these fans voluntarily go against the brand (see below). Some of them even go out of the way to "Like" the page only to abuse the brand.
While the brand presently has been doing its best in responding to the set of disgruntled customers, they just seem to keep coming. This has been one major problem with Facebook pages where civility and relevance of comments has gone for a toss.
For brand, it is disruptive two-way communication. Firstly, it interrupts their on-going narrative. Secondly, it scatters the customers whose queries might have been resolved more effectively had they gone through a proper channel (meant for resolution).
The problem is severe in case of service related sectors dealing with huge volumes such as telecom, hospitality, aviation etc. Even 1% increase in the number of dissatisfied customers means a much higher share of negative word of mouth.
This peculiar behavior points to a more important question - What is the objective of having a Facebook page?