HBO HD Gone AWOL

My HBO HD channel seems to have gone AWOL in the past 24 hours.  I
cannot even tune the cable box to the channel (it returns to the
previously tuned channel when I attempt to do so).  Two calls and an
email to Charter Communications and they claim that there is neither a
problem at my end or their end.  They claim that HBO must  not be
broadcasting a signal for HD.  Anyone else experiencing these
problems?

Thanks,

Mark