Condo board continues assessing owners incorrectly

As the Community Manager for a condo association I have made the Board aware that they have always assessed members wrongly. They have assessed by dividing expenses by the number of members, so that everyone pays the same assessment, and not according to the undivided interests, which are outlined in the Declaration. If the Board is unwilling to change their ways, and continue to assess members wrongly, what do I do?  North Carolina