I don't have the data to test. Try this update:
SELECT T0.CardCode 'Customer Code', T0.CardName 'Customer Name', T2.DocNum 'Payment#',T2.DocDate 'Pay Date',T0.[DocNum] 'Invoice#', T1.InstID,T0.DocDate 'Invoice Date', T0.DocDueDate, DateDiff(d,T0.DocDueDate,T2.DocDate) 'Overdue Days',T0.DocTotal 'Total', [SumApplied] 'Total Payment'
FROM [dbo].[OINV] T0 LEFT JOIN [dbo].[RCT2] T1 ON T1.[DocEntry] = T0.[DocEntry] LEFT JOIN [dbo].[ORCT] T2 ON T2.[DocNum] = T1.[DocNum] WHERE T2.Canceled='N' AND T0.Canceled='N' AND T0.CardName LIKE '[%0]%'
Order By T0.CardCode,T0.[DocDate] Desc