MANEUVERING FOR WX DEVS ALT CLRNC BECOMES UNCLR. VERIFICATION WITH ATC REVEALS DSCNT BELOW ARTCC'S DESIRED ALT.

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ON OUR DSCNT INTO MSY; THERE WAS A SMALL LINE OF TSTMS. OUR CURRENT ALT AT THE TIME WAS APPROX FL290. WHEN WE WERE GIVEN A DSCNT TO FL240; WE WERE ALLOWED TO DEVIATE AT WHICH TIME WE WERE DOING. ON OUR PRESENT HDG; WE WOULD BE PASSING BTWN 2 CELLS; WE ALSO HAD BUILDUPS RIGHT BELOW US AS WELL OF IN FRONT OF US; TOPS APPEARED TO BE FL180. THEN CTR GAVE US A DSCNT TO 11000 FT AND A XING RESTR; AT WHICH TIME WE TOLD HIM WE WERE UNABLE TO MAKE. CTR TOLD US TO MAKE A R 360 DEG TURN AND DSND TO 16000 FT. AS WE APCHED THE HDG WE WERE SUPPOSED TO ROLL OUT ON; CTR GAVE US A DSCNT TO 11000 FT; AND WANTED US TO DO ANOTHER 360 DEG TURN; AT WHICH TIME WE TOLD HIM IF WE DID IT WOULD PUT US RIGHT INTO THE BUILDUPS WHICH WE WERE DEVIATING FROM AS WELL AS A VERY SLOW DSCNT TO CLR THE TOPS AT 17000 FT AND 18000 FT. ONCE WE CLRED THE BUILDUPS AND THEY WERE BEHIND US; I BEGAN A RAPID DSCNT DOWN TO 11000 FT TRYING TO HELP THE CTLR OUT. PASSING 16000 FT; I ASKED THE FO IF HE WOULD VERIFY OUR CLRNC DOWN TO 11000 FT. CTR CAME BACK AND SAID NO; HE HAD ONLY GIVEN US A CLRNC DOWN TO 16000 FT AND WHAT WAS OUR ALT? WE TOLD HIM IT WAS 14200 FT AND THAT WE WERE CLBING TO 16000 FT. THE REST OF THE FLT WAS NORMAL. WHAT I BELIEVE HAD HAPPENED IS WHEN THE CTLR GAVE US THE 360 DEG TURN AND THE DSCNT DOWN TO 16000 FT THAT WAS THE LAST ALT HE HAD WRITTEN DOWN. SO WHEN WE ASKED TO VERIFY OUR DSCNT DOWN TO 11000 FT; THE CTLR LOOKED AT HIS PAD TO SEE WHAT HE HAD WRITTEN ON IT; AND HE SAW 16000 FT WHEN IN FACT IF HE WAS TO PULL AND LISTEN TO THE TAPES HE WOULD HAVE FOUND OUT WE WERE GIVEN A DSCNT CLRNC DOWN TO 11000 FT.