First check if this query works

SELECT approve.custcode, customer.custname, approve.fye,
service.payment_due , service.payment_recvd
FROM serviceapproval approve
INNER JOIN servicerendered service ON approve.fye = service.fye
AND approve.custcode = service.custcode
AND approve.effective_date = service.effective_date
AND approve.service_type = service.service_type
INNER JOIN customers customer ON approve.custcode = customer.custcode
AND approve.effective_date = customer.effective_date
WHERE date_of_service BETWEEN '1/1/2009' AND '12/31/2009'

If that works, then do

select a.custcode, a.fye, min(a.service_type)
from (SELECT approve.custcode, customer.custname, approve.fye,
service.payment_due , service.payment_recvd
FROM serviceapproval approve
INNER JOIN servicerendered service ON approve.fye = service.fye
AND approve.custcode = service.custcode
AND approve.effective_date = service.effective_date
AND approve.service_type = service.service_type
INNER JOIN customers customer ON approve.custcode = customer.custcode
AND approve.effective_date = customer.effective_date
WHERE date_of_service BETWEEN '1/1/2009' AND '12/31/2009') AS A
group by a.customercode,a.fye