SUM CASE WHEN CLAUSE
Assuming that the Ageing values match the names of the columns in your expected output, then this should work:

SELECT  *
FROM    (
    SELECT  BU, Ageing, NetDue
    FROM    [dbo].[vw_FACT_CONSOL_CREDITORS]
    WHERE   Date = @date
) src
PIVOT
(
    SUM(NetDue)
    FOR Ageing IN ([0-30], [31-60], [61-90], [91-120], [121-180], [181-365], [365+])
) piv


If they are not, then you will need to add some logic to the interior select statement to convert Ageing from whatever it is into those string values (e.g. '0-30', '365+').

As an example to check this, I did the following:

CREATE TABLE x (
    BU INT,
    NetDue SMALLMONEY,
    Ageing VARCHAR(10),
    Date DATE
)

INSERT x
VALUES 
  (1, 100, '31-60', '2017-04-01'),
  (2, 25.47, '31-60', '2017-04-01'),
  (1, 90.17, '31-60', '2017-05-01'),
  (1, 16.42, '181-365', '2017-04-01'),
  (2, 99.99, '365+', '2017-04-01')

SELECT  *
FROM    (
    SELECT  BU, Ageing, NetDue
    FROM    x
    WHERE   Date = '2017-04-01'
) src
PIVOT
(
    SUM(NetDue)
    FOR Ageing IN ([0-30], [31-60], [61-90], [91-120], [121-180], [181-365], [365+])
) piv


which produced the output:

BU  0-30    31-60   61-90   91-120  121-180 181-365 365+
1   NULL    100.00  NULL    NULL    NULL    16.42   NULL
2   NULL    25.47   NULL    NULL    NULL    NULL    99.99


All the information (and more) for determining this logic can be found here.