You have noticed the same issue three times. You have hinted at it twice. Now you are frustrated that nothing has changed.
The other person may have no idea you were asking for a change.
A useful difficult conversation is specific and timely. Describe what happened, explain its effect, and say what you need going forward.
“When the update came after the deadline, I could not complete the report on time. Can you send it by noon on Thursdays, or let me know on Wednesday if that will be difficult?”
That gives the person something they can respond to. It also leaves room to learn what may be getting in the way.
Is there a conversation you have been hinting at when you need to have it clearly?
