I'm using a Sumproduct formula (see below) that whilst it returns zero, the
3rd Array when view by pressing the = sign on the edit bar reads the account
numbers that match the criteria eg. ["A123";"A345","A678"}. What I now need
to do is use the returned account numbers to look up another table for a
debt figure.

Some help is required therefore to add a 4th or 5th Array.

=SUMPRODUCT(--(sales!E2:E300<=15),--(Sales!E2:E300),(Sales"A2:A300))

Thanks, Rob