Sometimes it isn't what you say, but how you say it
I spoke to one of the feeders today who called to say that the town councils, AVA and the NEA were rude to her. She is a well meaning woman who wants to help but when I asked her what happened, she mentioned that when they called with a complaint (admittedly a rather ridiculous one - that a cat defecated on top of the car), she asked them, if someone claimed a cat killed a person would they believe them too and started arguing with them. She made a good point, but I think it's the way she did it - unfortunately the town council got upset with her. Then she went to the MP and complained and went back and told the town council she had complained about them. Relations have thus deteriorated.
The woman is entirely right in saying that the town council should investigate and that the complaints may be ludicrous sometimes. However, if the caregiver is argumentative and doesn't seem like they want to solve the problem, some officers may be put off dealing with them again because they seem unreasonable. For example, if you argue with the officer, they'll wonder if you can really do a mediation with a complainant, who may also be upset.
So hard as it can be, and it CAN be hard, try to keep your calm. If the person is very rude, then just take down their details and lodge a complaint. Of course it goes without saying that courtesy goes both ways - no one is going to be very sympathetic if you were the one who was rude first.