Запрос который находит ошибку вне зависимости от даты
select
c.account_no, s.name, c.customer_id
from PERSONAL_TARIF P1
inner join customer c on (c.customer_id = p1.customer_id)
inner join services s on (s.service_id = p1.service_id)
where exists(select
*
from PERSONAL_TARIF P2
where P2.TARIF_ID <> P1.TARIF_ID
and P1.CUSTOMER_ID = P2.CUSTOMER_ID
and P1.SERVICE_ID = P2.SERVICE_ID
and P2.DATE_FROM between P1.DATE_FROM and P1.DATE_TO)