Never heard of "week long laundry service" on any of our 25+ HAL cruises. We get laundry and dry cleaning included in the suite fare but have never heard of anyone paying other than the rate listed on the form for each individual garment.
There are washers and dryers available for pax use.
Perhaps this service is new. If so, I think it's a great idea.
We were on the Statendam 6/10, and for one set price of $35.
we could have all of laundry cleaned for the entire week. There
was a two day turn around time, but still it was worth it
especially since the three of us (wife, son, and yours truly)
had spent some time in Alaska before boarding.