B737 CREW HAD LAST MIN CLRNC CHANGE INTO LAX. CTLR WAS ALSO CONFUSED.

Narrative

INBOUND TO CIVET ON J107 FOR LAX. PRIOR TO CIVET; ZLA CLRED US DIRECT SNRKL FOR THE MITTS ARR INSTEAD OF THE CIVET ARR. WE REQUESTED A VECTOR DUE TO OUR ACFT STATUS; BUT HE SAID AGAIN 'CLRED DIRECT SNRKL.' WE FINALLY CONVINCED HIM WE COULDN'T NAV DIRECT SNRKL; SO HE CLRED US TO INTERCEPT THE ARR AT CIVET. A HVY JET WAS AHEAD OF US AND HE TOLD US 'CLRED THE MITTS ARR TO RWY 25L; THE HVY IS FOR RWY 24R.' THAT CONFUSED US; SO WE ASKED FOR CLARIFICATION AND HE SAID THE HVY WAS RWY 25L AND WE WERE CLRED TO DSND VIA THE MITTS ARR TO RWY 24R. SOMEWHERE IN ALL THIS HE SLOWED US TO 210 KTS. WE CONTINUED DOWN THE RWY 24R ILS AND AROUND 4500 FT HE CALLED AND WANTED TO KNOW WHY WE HADN'T SWITCHED TO SOCAL ON 125.80 (I THINK). WE TOLD HIM WE WERE NEVER GIVEN A FREQ CHANGE AND HE REPLIED 'THEN YOU SHOULD NOT HAVE DSNDED!' WE SWITCHED TO SOCAL AND CONTINUED APCH. ATC SEEMED TO BE CONFUSED A GOOD PART OF THE TIME WHICH KEPT US CONFUSED. I DON'T THINK HE (ZLA) EVER GAVE US A FREQ CHANGE; BUT IN RETROSPECT; I'M NOT SURE WE EVER ACTUALLY RECEIVED AN APCH CTLR TO RWY 24R; JUST A DSCNT CLRNC FOR THE MITTS ARR. THIS AREA IS ALWAYS A VERY BUSY TIME BECAUSE THEY ALWAYS SEEM TO CHANGE YOUR ARR AND RWY AT THE LAST MIN. THROW IN A CONFUSED CTLR; AND IT MAKES IT EASY FOR AN OVERWORKED CREW TO KEEP TRACK OF ALL THEY NEED TO BE KEEPING TRACK OF.