I work in this company for over 15 years as a software developer. During the last years employees have left the company again and again and I have taken over their work. This includes work like administration and helpdesk. These jobs are deeply repugnant to me. I do not like them and I am neither qualified nor trained for them. My colleagues know how unhappy I am but my direct manager doesn't seem to notice. Or he ignores it. He gives me more of that kind of work.
I'm already looking for a new job. Should I still tell him how unhappy I am or is it better to accept it in silence until I quit?