In article ,
Jalal wrote:

I have tried to add it to the SUMPRODUCT formula you initially suggested but
get an impossibly HIGH answer - it cannot be correct

e.g. this is the formula i created
=SUMPRODUCT(--(D2:$D$65536=T2),--(E2:$E$65536=U2)--(C2:$C$65536=V2))

Any suggestions?

There's a comma missing between the second and third argument. Try...

=SUMPRODUCT(--(D2:$D$65536=T2),--(E2:$E$65536=U2),--(C2:$C$65536=V2))

Also, if your data does not actually extent all the way to Row 65536 and
you're using Excel 2003, convert your data into a list...

Data List Create List

The ranges will automatically adjust as data is added/removed. If
you're using an earlier version, you can use dynamic named ranges.

--
Domenic
http://www.xl-central.com