THE CTLR STATED THE TFC HE WAS FOLLOWING WAS A B757 AT 5 MI. THE RPTR STAYED HIGH BUT ENCOUNTERED WAKE AT 300 FT AGL AND WENT AROUND.

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FLT XXX IN A DO328 ON APCH TO RWY 32 AT PITTSBURGH INTL ARPT. 32 PAX WERE ON BOARD AND WE WERE IN NIGHT VMC CONDITIONS BEING VECTORED FOR AN ILS TO RWY 32. THE CTLR TOLD US THAT OUR TFC WAS A B757; 5 MI AHEAD; AND ASKED IF WE HAD HIM IN SIGHT. WHEN WE STATED THAT WE DID THE CTLR SAID 'CLRED THE VISUAL; MAINTAIN 170 KTS TO THE MARKER; AND CONTACT TWR.' ABOUT 20 SECONDS LATER AFTER WE COMPLETED OUR TURN TO FINAL I NOTED ON THE TCASII THAT WE WERE NOT 5 MI BUT 2 1/4 MI BEHIND THE B757. WE MAINTAINED 1 DOT HIGH AND L OF COURSE TO AVOID THE WAKE. WHEN WE HAD TO ALIGN WITH THE RWY FOR LNDG SEVERE WAKE TURB CAUSED US TO GAR. I AM VERY CONCERNED WHEN CTLRS VIOLATE SPACING AND THEN LIE TO THE ACFT THEY ARE CTLING TO GET THEM TO ACCEPT THE VISUAL. SUPERVISORY PERSONNEL AT PITTSBURGH APCH ALLOW THIS TO HAPPEN FREQUENTLY. I HAVE BEEN TOLD BY CTLRS AT PITTSBURGH THAT IF THEY CAN'T HANDLE THE TFC THAT THEY WILL BE REPLACED. I DO NOT UNDERSTAND HOW THE FAA CAN CONDONE VIOLATING REGS WHEN SAFETY OF PAX ARE INVOLVED; JUST TO WORK A LARGER VOLUME OF TFC THAN CAN BE SAFELY DONE. GETTING ACFT TOO CLOSE AND THEN CLRING THEM FOR THE VISUAL SEEMS TO BE A TECHNIQUE USED AT PITTSBURGH APCH. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED HIS ACFT HAD THE ADVANCED AUTOMATED COCKPIT. HE STATED WHEN HE TURNED BASE TO FINAL THERE WAS NOT THE 5 MI THE CTLR CLAIMED. SHOWN ON HIS TCASII WAS ONLY 2 1/4 MI. THE CTLR ALSO ASSIGNED 170 KTS WHICH SEEMED FASTER THAN THE ACFT HE WAS SUPPOSED TO MAINTAIN SPACING ON. THE RPTR SAID HE HAS EXPERIENCED MORE VIOLENT AND LARGER ROLL EXCURSIONS BUT NEVER SO CLOSE TO THE GND. THE ROLL WAS ABOUT 20 DEGS TO THE L AND ABOUT THE TIME HE GOT THE WINGS BACK LEVEL IT ROLLED 20 DEGS TO THE R WHEREUPON HE DECIDED TO GAR.