You've got more than FDCPA violations you got BK law violations !!! BK court can and will slam anyone caught attempting to collect on a discharged debt, so I'd use that law rather than the FDCPA.
Send the creditor/collector a cease and desist letter (look at
www.creditinfocenter.com for one). In it you tell them that you filed bankrupcty, case # xxxx, filed xx/xx/xx, and discharged xx/xx/xx and that they were included (send a copy of the creditor matrix if you can as proof). Then you tell them that if they do not immediately cease an desist ALL collection efforts, you will file a Motion for Contempt and Request for Sanctions against them with the bankrupty court.
If that doesn't make them stop, then you go from there, but it should. Most of the time, the left hand doesn't know what the right hand is doing but you need to be very firm from the start and let them know that YOU know they're in deep doo-doo for trying to collect on a discharged debt.