De or het klachtregeling?

The correct Dutch article is:

de klachtregeling

Rule Words ending in -ing: almost always de. See the rule

How to use klachtregeling

the klachtregelingde klachtregeling
this klachtregelingdeze klachtregeling
that klachtregelingdie klachtregeling
our klachtregelingonze klachtregeling
your klachtregelingjouw klachtregeling
every klachtregelingelke klachtregeling
which klachtregeling?welke klachtregeling?
a big klachtregeling / the big klachtregelingeen grote klachtregeling, de grote klachtregeling