When you got hired

HR: please come to us if there's any problems related work so that we can give a solution.

After years of working you send a mail with you problems, it's been months. Still no reply! And try to avoid conversation regarding that problem.

HR does not exist to help you deal with your company, they exist to help the company deal with you. If there's a conflict between you and the company its in their best interest to come up with a solution that benefits the company as much as possible. You as an employee don't decide if they get fired and you don't cover their paycheque. HR can sometimes be helpful/useful, especially if there's no conflict involved (eg you need help navigating some kind of third party bureaucracy) or if the conflict is between you and someone the company values less than you. But don't make the mistake of thinking they're a resource for you, that's just something they say.

HR told me that i had to discuss the salary offer because there was quite some space for a higher salary.
They really should serve the emoyees and in some companies they really do. Get a better job if you dont like it.