Tuition Waiver setup

I have a situation between a waiver and other higher priority payment items.

X student gets a non-refundable tuition waiver for 1300 (predetermined), and X student's tuition was 1600. The excess 300 is a repeat fee not eligible to be covered by the waiver. Student has a balance of 300 but all other eligible expenses have been covered otherwise.

Later, student X gets a Pell grant (500) and another scholarship (250) that are higher priority payment items over the waiver, totaling 750 dollars to be applied before the waiver. That 750 is applied, and we expected the waiver to reduce by the amount of the difference between the 2 new awards and the existing 300 balance, since these awards DO cover the repeat fee. So (750 - 300 = 450). It applies the entirety of the waiver and tries to refund the 450 difference rather than just reducing the waiver. This waiver is NOT supposed to be refundable, it