LTT ACFT ON DEP CLBOUT; AVOIDING TSTMS; WAS RECEIVING ALT CLRNCS FROM DEP CTLR. WHEN SWITCHING TO CTR FREQ THE CTLR ASKED FLC WHO ASSIGNED THE ALT OF 17000 FT AND THEN RECLRED THEM TO DSND TO 8000 FT.

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TSTMS IN THE VICINITY PREVENTED US FROM FLYING OUR NORMAL DEP. WE DEPARTED RWY 20 AT BMI AND TURNED TO THE E. OUR TKOF CLRNC ALT WAS AMENDED BY BMI TWR TO 9000 FT. WE CONTACTED PEORIA DEP AND TOLD THEM OF OUR DEV FOR WX. PEORIA DEP (118.05) THEN INSTRUCTED US TO CONTACT ZAU ON 132.5. WE DID SO AND THEN WERE TOLD TO CLB TO 17000 FT. WE ACKNOWLEDGED 17000 FT AND STARTED OUR CLB. I ADVISED CTR WE WERE ON A 060 DEG HDG FOR WX AND THEN WOULD BE ABLE TO TURN TO A 360 DEG HDG TO BRING US BACK TO OUR NORMAL RTE. HE DID NOT RESPOND TO US BUT WAS BUSY TALKING TO OTHER ACFT ON DIFFERENT FREQS THAT WE COULD NOT HEAR. WHEN I REQUESTED DIRECT O'HARE HE ASKED US OUR POS. WE SAID OUR POS E OF PONTIAC AND CTLR TOLD US TO GO BACK TO OUR LAST ASSIGNED FREQ. BACK ON WITH PEORIA DEP; HE GAVE US 2 DIFFERENT NEW FREQS TO TRY AND THEN SAID TO JUST STAY WITH HIM. HE THEN SAID SWITCH TO 123.75. UPON CONTACT; THE CTLR ASKED US WHO HAD ASSIGNED US 17000 FT AND INSTRUCTED US TO DSND TO AND MAINTAIN 8000 FT. WE TOLD HER WE HAD BEEN ASSIGNED 17000 FT BY 132.5 AND HAD ACKNOWLEDGED 17000 FT ON 132.5. WE DSNDED DOWN TO 8000 FT FROM APPROX 12000 FT. THIS CTLR ACTED AS IF 17000 FT WAS AN INCORRECT ALT AND THERE WAS OBVIOUS CONFUSION BTWN THE DIFFERENT CTLRS. I FEEL THE 132.5 CTLR MAY HAVE BEEN OVERLOADED WITH MULTIPLE FREQS.