Transferred services charged as a disconnect

've been a comcast customer for a long
time for internet. Decided in May of this
year to get home security. Have been
paying on it since. Called to transfer
services in November since we were
moving to a new address in the same city
that was compatible with comcast.
Moved and received bill stating we owed
over $1000. Our service is due to be
interrupted tomorrow if we don't pay. We
have NEVER paid late until this bill. Have
talked to numerous live agents as well as
over the phone with agents. Have been
told many times it would be fixed but has
not happened. Would like to stay with
comcast but we just bought a house and
are not going to pay over $900 more than
our regular bill for equipment we've had
and that was simply transferred. Make it
make sense.