De or het klantbediening?

The correct Dutch article is:

de klantbediening

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

How to use klantbediening

the klantbedieningde klantbediening
this klantbedieningdeze klantbediening
that klantbedieningdie klantbediening
our klantbedieningonze klantbediening
your klantbedieningjouw klantbediening
every klantbedieningelke klantbediening
which klantbediening?welke klantbediening?
a big klantbediening / the big klantbedieningeen grote klantbediening, de grote klantbediening