ATX X HAD LTSS WITH ACFT Y ON APCH. SYS ERROR.

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X WAS ON AN IFR FLT PLAN FROM MOD TO OAK IN BE-99 AS PIC. I WAS HANDED OFF TO BAY APCH ON VECTORS DIRECT TO OAK FROM STOCKTON APCH; LEVEL AT 6000 FT MSL. AFTER CHKING IN WITH BAY APCH; I WAS ASSIGNED A 230 DEG VECTOR TO INTERCEPT THE OAK RWY 27R LOC AND DSND TO 3200 FT MSL. I READ BACK THIS CLRNC AND PLACED RWY 29 ILS ON REQUEST. BAY ACKNOWLEDGE MY REQUEST BY STATING; 'I HAVE YOUR REQUEST.' AT THE APPROPRIATE TIME I TURNED TO INTERCEPT THE RWY 27R LOC. I RECEIVED A CLRNC FROM BAY TO TURN L TO 200 DEGS IMMEDIATELY. AT THIS POINT I WAS INSTRUCTED TO FLY THIS VECTOR THEN ANOTHER VECTOR OF 260 DEGS AND 3000 FT MSL TO INTERCEPT AND FLY THE ILS 29 AT OAK. I UNDERSTAND THAT THERE WAS A LACK OF SEPARATION ON THE LOC FOR RWY 27R. I WAS IN IMC CONDITIONS AT THE TIME SO CANNOT MENTION THE PROX OF THE OTHER ACFT. I WAS INSTRUCTED TO CALL THE SUPVR ON DUTY AT BAY APCH AFTER LNDG. AFTER REVIEW OF THE TAPES; CTLR ERROR WAS THE CONCLUDING FACTOR. THE CTLR THOUGHT HE HAD GIVEN ME AN AMENDED CLRNC FOR RWY 29 ILS AT OAK; WHICH WAS NOT THE CASE.