Unless you have the screen zoomed right, the minus sign on a refund can be missed. Please ensure that the column width for the amount is always sufficient to show the minus sign for a refund on the same line as the amount
In the attached screenshot, the net VAT due of £1,411.60 is in fact a repayment - the minus sign is on the previous line. Panic and time wasting would be avoided with a better rule for the column width