Is anyone else finding their server being blocked by CONCENTRIC.NET?

We got cut off around the beginning of the month and have been getting
an unbelievable run-around.  First they cut us off without warning and
then the following pattern repeats:  A concentric subscriber or list
owner asks where their mail is and is told SJU has a problem.  We provide
logs showing time-outs at the other end.  Concentric then says we were
blocked for SPAM.  We say the dedicated server has no users to send SPAM,
doesn't relay and has a clean bill of health with ORBS, please show us
an example.  We're then told that we were cut off for "excessive mail"
during the last week... after the block was in place.  We have logs showing
(ta-da) we didn't transmit any mail down a dead wire.  They then tell us
that they are CURRENTLY working to resolve the problem with the SJU
administrators, which happen to be me, and only me.  I check all over my
cubicle, under my chair, in my drawers etc and am unable to figure out
who I'm supposedly talking to.  They then announce that the problem will be
resolved by calling and asking for X.  I dial the given number and am
handed to X, a pleasant system administrator who hears me out and assures
me that they have NO spam reports, no volume problem, no other issues
and no record of blocking us.  He tells me he'll investigate and get
right back to me.  Then, poof, he winks out of existence.  I'm now back
to the "please call..." stage.  Meanwhile, other subscribers are going
through the same process, from the beginning, concurrently, sometimes
with the same people, but out of synch.  Honest.  Concentric is running
people through the above sequence at different speeds and times.

One subscriber at Concentric managed to dance the whole jig from begining
to end today, and mentioned that this was being done to another commercial
list distribution service he _owns_ lists on (not Listserv based).

Could someone clue me in here?  Thanks.
                                                    -Kary