FLT CREW OF A320 DSNDED BELOW CLRED ALT ON DSCNT TO DTW WHEN APCH CTLS FAILS TO RECOGNIZE THEY READ BACK 10000 FT INSTEAD OF 11000 FT.

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ON ARR TO DTW; WE WERE DELAYED. INITIALLY WE WERE ISSUED HOLDING AT GIBER ON THE POLAR 1 ARR. ATC DECIDED TO HOLD US CLOSER TO DTW SO THEY CANCELED THE GIBER HOLD AND HAD US CONTINUE ON THE ARR. WE SLOWED AND CONTINUED ON THE ARR AND WERE ISSUED HOLDING AT POLAR INTXN ON THE ARR. WE HELD FOR 20+ MINS AND WERE CLRED TO CONTINUE WITH THE ARR. CTLR HAD ASSIGNED A HDG; PASSING SCUBI INTXN; TO 150 DEGS. APCHING SCUBI; THE CTLR ISSUED A DSCNT CLRNC TO 10000 FT. I READ BACK 10000 FT AND SET THAT ALT IN THE MCP. BOTH PLTS COMPLIED WITH THE SOP BY POINTING AT THE NEW ALT AND THE PF REPEATED THE ASSIGNED ALT. APCHING 10200 FT; THE CTLR INDICATED WE WERE ONLY CLRED TO 11000 FT AND TOLD US TO CLB IMMEDIATELY BACK TO 11000 FT. I AM CERTAIN HE PREVIOUSLY ISSUED 10000 FT. CTLR DID NOT INDICATE THERE WAS ANY CONFLICT. MIN OR 2 LATER; CTLR ISSUED FREQ CHANGE TO 125.95; WHICH WAS READ BACK. THE FREQ WAS IN ERROR. WENT BACK TO THE ISSUING CTLR AND HE SAID HE GAVE US 125.15. AFTER OUR PREVIOUS EXPERIENCE WE WERE LISTENING VERY CLOSE AND THE CTLR INITIALLY ISSUED 125.95. CAPT DID CALL DISPATCH AND RPTED THE ALTDEV. CTLR HEARBACK WAS NOT OCCURRING EFFECTIVELY. THE VISIBILITY WAS GOOD BUT THE WIND WAS OUT OF THE W GUSTING TO 38 KTS WHICH WAS AFFECTING ARPT OPS. AFTER THE ERROR ON MY FIRST RPT ATTEMPT; I REALIZE THAT I WAS MORE FATIGUED THAN I REALIZED.