I often give feedback on service - good or bad. A lot of my working life was in customer facing roles, including managing front line council services, which was fun! Not. People who wanted the impossible, demanding 'their rights' (they were usually wrong), and generally angry with their lot and looking to blame others. I was also active in training staff in dealing with complaints.
We could diffuse most situations, we took the time to explain clearly what was available, what we could help with, directed people to the services they needed, often making initial contact for them. Unfortunately there are some people who approach every situation belligerently, and take everything personally. Those were the customers I'd kill with kindness!
I took our endowment insurers through their complaints system and got the £4k I wanted.