Thank them for the feedback
Start by showing you value their input.
Restate what was agreed
Quote the number of revision rounds in the scope.
Say where you are
Tell them how many rounds are used and what remains.
Offer a paid extra round
Give a clear price and timeline for additional revisions.
Suggest how to get the most from the next round
Ask them to batch feedback in one list.
Confirm the next step
Say what you need from them and when you will deliver.