  To investigate the completeness of coupled channel (CC) Breit-Pauli R-Matrix
(BPRM) calculations for opacities, we employ the relativistic distorted wave
(RDW) method to complement (``top-up'') and compare the BPRM photoionization
cross sections for high-$n\ell$ levels of both FeXVII and FeXVIII. Good
agreement is found in background photoionization cross sections using these two
methods, which also ensures correct matching of bound level cross sections for
completeness. In order to top-up the CC-BPRM calculations, bound-bound
transitions involving additional bound levels, and a large number of
doubly-excited quasi-bound levels corresponding to BPRM autoionizing resonances
described in paper RMOPII, are calculated using the RDW method. Photoionization
cross sections in the high energy region are also computed and compared up to
about 500 $Ry$, and contributions from higher core level excitations than BPRM
are considered. The effect of configuration interaction is investigated, which
plays a significant role in correctly reproducing some background cross
sections. Owing to the fact that the additional RDW levels correspond to
high-$n\ell$ bound levels that are negligibly populated according to the
Mihalas-Hummer-D\"{a}ppen equation-of-state (Paper I), the effect on opacities
is expected to be small.
