  The three dimensional perovskite manganites in the range of hole-doping $x >
0.5$ are studied in detail using a double exchange model with degenerate $e_g$
orbitals including intra- and inter-orbital correlations and near-neighbour
Coulomb repulsion. We show that such a model captures the observed phase
diagram and orbital-ordering in the intermediate to large band-width regime. It
is argued that the Jahn-Teller effect, considered to be crucial for the region
$x<0.5$, does not play a major role in this region, particularly for systems
with moderate to large band-width. The anisotropic hopping across the
degenerate $e_g$ orbitals are crucial in understanding the ground state phases
of this region, an observation emphasized earlier by Brink and Khomskii. Based
on calculations using a realistic limit of finite Hund's coupling, we show that
the inclusion of interactions stabilizes th e C-phase, the antiferromagnetic
metallic A-phase moves closer to $x=0.5$ while th e ferromagnetic phase shrinks
in agreement with recent observations. The charge ordering close to $x=0.5$ and
the effect of reduction of band-width are also outlined. The effect of disorder
and the possibility of inhomogeneous mixture of competing states have been
discussed.
