I was in a role to take customer calls for years, and did straight up support for a while early in my career. I found that if I took a genuine interest in their problems, and an interest in the individual, it turned a lot of bad attitudes around. Someone calls and is angry, frustrated with the thing we’ve made, it was my job to help them, not just fix the issue but feel happy with the product, too. That being said, there’s no helping some people, and some products may be too bad to rightfully support.