That being said in my experience when a customer starts complaining the company providing the service usually holds their breath, and without being offensive (even if the customer is) deals with the situation at hand in the proper manner.
I deal with Fortune 100 and Fortune 500 companies every day. I am a software developer and I hear numerous complaints by my customer, but RARELY have any of them been rude and condescending in the manner in which they relay their complaints ... it's a 2 way street ... they vent, but they vent in a civilized manner and the problems are addressed.
If they don't, and I have had occasions where they don't, I have to hold my breath because I am not the Owner/CEO of my company ... If I was, then I could make the decision to tell them to pack it where the sun don't shine. I would be the the final decision maker of whether I want to continue to do business with them or not ... and if they were to treat me or my employees with disrespect, then I don't want their business.
In the 30+ years I have been doing this, I have had 1 VP attack me personally in a meeting ... I set him straight, in a civilized manner, but I didn't let him get away with it.