I love these threads. To the OP, those guys that are not returning discs are douche canoes. You are karmically allowed to set their car on fire by lighting a bag of feces in the drivers seat of said car. However explaining to law enforcement why you are justified in committing arson will be a little bit difficult.
Don't blame DGCR for this reaction, this topic has been beaten to death, revived, beaten to death, revived again, beaten to death, revived yet again, land filled, and beaten to death with less restraint down there, and revived.
If you are doing the right thing, calling number and making reasonable attempts to return discs then you are cool. F#%k those other guys.