FAILURE TO BLACKLIST THE ******/MISSING PHONE

I BOUGHT A NEW DEVICE (SAMSUNG A3, WHITE, IMEI NO: ***, CELL NO: ***) ON THE 2ND OF APRIL AT CELL C HATFIELD PLAZA. I WAS HANDED A PHONE BUT THEY DIDN'T HAVE A NANO SIM IN STORE. AS A RESULT, THE SIM CARD WAS NEVER INSERTED ON THE DEVICE & I WAS TOLD TO COMEBACK SOME OTHER DAY TO COLLECT A NANO SIM. DUE TO MY BUSY SCHEDULE, I LEFT THE COUNTRY AND WHEN I RETURNED, THE PHONE WAS MISSING. I CALLED CELL C TO BLACKLIST THE DEVICE BUT I WAS TOLD IT IS IMPOSSIBLE TO DO THAT BECAUSE NO SIM CARD WAS EVER INSERTED ON THE DEVICE. YES IT WAS NEVER INSERTED FOR OBVIOUS REASONS, YOU NEVER HAD A NANO SIM IN STORE. NOW I AM CAUGHT BETWEEN A HARD SURFACE & A ROCK. I WAS TOLD THAT I MUST INVESTIGATE TO FIND THE NUMBER WHICH MIGHT HAVE BEEN USED ON THE DEVICE, SO THEY CAN BLACKLIST IT. WORSE IM TOLD THE DEVICE IS NOT LISTED ON YOUR NETWORK. IT IS MY RESPONSIBILITY TO REGISTER IT ON YOUR NETWORK? WHY ARE YOU EVEN DEBITING MY ACCOUNT FOR SOMETHING YOU HAVE NO RECORD OF? I NEED THIS DEVICE BLACKLISTED ASAP. SOMEBODY PLEASE HELP