I'm just baffled that this could even occur, what if it had ended up being some elderly person that just paid the bill.  

I'm not sure what a list-serve is, but they need to come up with a better plan for this type of thing.   

The agent I spoke with (their name was at the bottom of the notice) went in and took my clients address off that other persons account, but it should have never ended up there to begin with.