ノックしろと何度も <blank> ってるでしょ！
And this is the actual image:
I think I understand what the sentence is trying to say (I'm still very much a beginner at japanese), something like "How many times do I have to tell you to knock before you come in!" (in a previous panel the character in the comic says "おはようございま。。。" as he's opening a door to a room without knocking).
Anyway, thanks in advance if anyone has any ideas!
