keep on at
keep (going) on at (one)
To persist in reprimanding or criticizing one. If you keep going on at the investors, they're apt to get angry and leave.
keep on at (one)
To nag one about something. The doctor always keeps on at me about eating better. Ugh, my mom keeps on at me all the time about my grades, but I just have no interest in the classes I'm taking this semester.
keep (going) on at someone or something
to continue to complain about or scold someone or a group. Don't keep going on at him. Give him the dickens and be done with it. Please don't keep on at the committee. They did the best they could.