continue to receive someone else's mail; AT&T customer service tells me to just throw them away?

I have been receving another person's mail at my residence now for months, and despite multiple attempts at putting 'return to sender; does not reside at this address' to send back to AT&T, I continue to receive this individual's statement. In the past two days, I actually received multiple statements (5) for this individual. I contacted AT&T customer support and was told there was nothing they could do, and to simply throw this person's mail away. Is there nothing that can be done about this? I've lived at this residence for 10 years and do not know the individual whose mail I keep receiving.