HOW DO I GET IP'S?

Can anyone suggest a good way to get a CIDR block from the
internic? We are two separate isps with separate ASNs, merged under one
corporation,
with one of them currently getting addresses from an upstream provider
(/20). The problem is that in that location we are out of addresses, are
multi-homed, and
dissatisfied with our current provider. We need addresses before we can
switch over, but the internic refuses to release any to us until we have
used another /20 from our current provider. Thus, the internic has
forced us to use one carrier with poor service. Legally, is this a
monopoly? Has anyone started a class action suit? Can anyone help us?