Students who always complain

I hate my 6 o'clock class. They don't do anything but to complain. It's very stressful to teach them. I remember when I first taught them, they couldn't read or write even a single word like "she" or "they". It always took us 30 minutes to read and learn the spelling of ten of the sight words. And now I can say that they improved a lot. They can't only read fast but they can also write and explain even hard words. Of course that wasn't an easy job. I always argue with them everytime we meet. They always say that I always give them hard works. We have to learn words, explain what they have read, study the pronunciation and give homeworks. They said they haven't studied like that before. I know that's why they were stupid. Actually, I also taught them phonics on my first month of meeting them because they couldn't read or write. But until now it's hard to correct their pronunciation because whenever I teach them the correct pronunciation, they get angry easily so sometimes I'd rather ignore them because I get much stress.

Before we start the class, they always tell me to study a little and leave early. That's everyday that I always want to put earphone on my ears before I start the class. I don't hate them but I hate their bad attitudes with regards to studying. I always want them to learn but they are not interested enough. Do I get more salary if they learn a lot? Of course not! Would my salary decrease if they don't learn? Absolutely not! I just want to do my job so I'm trying my best so that they could learn. They should know that! Yes, they should!