Min/ Max dates based on results of query
This should work to get the min and max date for you.

SELECT MIN(RAISED_DATE), MAX(RAISED_DATE), MIN(COM_DATE), MAX(COM_DATE)
FROM   (SELECT SO.COM_DATE, SO.RAISED_DATE, SE.SERV_NO, SO.OR_NO
        FROM S_ORDER SO, S_SERV SE
        WHERE SO.CU_NO='286243' AND SE.SERV_NO='69780'
        AND SUBSTR (SE.ACCT_NO, 1,8)=SO.CU_NO
        AND SO.RAISED_DATE +4/24 BETWEEN TO_DATE('2017-11-01','YYYY-MM-DD')
        AND TO_DATE('2018-07-30','YYYY-MM-DD'))


If you want the other data in the query you will need to add a group by

SELECT SO.COM_DATE, MIN(SO.RAISED_DATE), MAX(SO.RAISED_DATE), SE.SERV_NO, SO.OR_NO
FROM S_ORDER SO, S_SERV SE
WHERE SO.CU_NO='286243' AND SE.SERV_NO='69780'
AND SUBSTR (SE.ACCT_NO, 1,8)=SO.CU_NO
AND SO.RAISED_DATE +4/24 BETWEEN TO_DATE('2017-11-01','YYYY-MM-DD')
AND TO_DATE('2018-07-30','YYYY-MM-DD')
GROUP BY SO.COM_DATE, SE.SERV_NO, SO.OR_NO