NMAC SYS ERROR.

Narrative

WHEN 3 NM SE OF CCR; WAS CLRED TO LAND STRAIGHT IN TO RWY 32R. OTHER ACFT; A HIGH WING SMA; CALLED ON R DOWNWIND FOR LNDG. HE WAS INSTRUCTED TO TURN BASE AND CLRED TO LAND AHEAD OF ME. HE STATED HE DID NOT HAVE ME IN SIGHT. TWR ASSURED HIM NO CONFLICT. TWR TOLD US HE WAS 1 MI AHEAD OF US AND INSTRUCTED ME TO MAKE S-TURNS. WE THEN SAW HIM AT OUR 03:30 POS; 50 FT ABOVE AND 150 FT LATERALLY; TURNING FROM BASE TO FINAL AND HEADED STRAIGHT AT US. WE WERE AT THIS TIME FULL FLAPS AND GEAR DOWN AND LESS THAN 1 MI FROM THRESHOLD. TO AVOID COLLISION; WE MADE IMMEDIATE 360 DEG L TURN AND CLEANED AIRPLANE UP; FULL PWR. WE RETURNED TO LAND. AFTER LNDG WE HEARD OTHER PLT TELL CTLR HE WAS SORRY HE CAUSED A PROB. CTLR TOLD HIM 'NO PROB.' WE STATED ON TWR FREQ WE CERTAINLY FELT THERE WAS A PROB. WE CALLED TWR ON LANDLINE AFTER PARKING; BUT WAS UNABLE TO TALK TO LADY CTLR. HER SUPVR SAID IT WAS A 'JUDGEMENT CALL.' CTLR AND SUPVR WERE BOTH FLIPPANT. I FEEL CTLR HAD POOR DEPTH PERCEPTION; EVEN POORER JUDGEMENT AND VERY POOR ATTITUDE.