---Temp---Pls remove 2005-July-20
	update SIEBEL.CBR_PROD_BAL set eod_bal=999999999999
	WHERE eod_bal>9999999999999;
	---End emove block

SELECT ATTRIB_03  FROM SIEBEL.S_CONTACT_FNXM WHERE ATTRIB_06=V_ATTRIB_06 AND LENGTH(ATTRIB_03) =V_ASSET_LENGTH)
		MINUS
		(SELECT ASSET.ASSET_NUM PID  FROM SIEBEL.S_ASSET ASSET, SIEBEL.S_PROD_INT PROD
		WHERE ASSET.PROD_ID=PROD.ROW_ID AND 
		PROD.DETAIL_TYPE_CD IN(V_PRODUCT_TYPE_SVNG,V_PRODUCT_TYPE_TD)
		AND LENGTH(ASSET.ASSET_NUM) =V_ASSET_LENGTH))
--run explain plan for this statement and check its output.

Similarly check the explain plans for the update statements like:
UPDATE SIEBEL.CBR_PROD_BAL  SET  DAT_LAST_MNT = V_MAX_FILE_DATE
				WHERE COD_CUST_NATL_ID = tblMissingPID(nRowCounter);
 are they using indexes are doing full table scans?

One more thing in the code is:

[B]SET TRANSACTION USE ROLLBACK SEGMENT SBP_BIG_RBS;[/B]

Instead of using RBS , consider using Undo tablespace.