If you have a low-cost ISP, named anything basic like The Net, and you want to raise ARPU. All you have to do is understaff the call center - with unqualified staff, naturally. And charge 0.45 EUR/min. Make sure people need to sit through a lengthy menu to begin with.
This appeared to be KPN's strategy of its Het Net subbrand. It was exposed at a TV show covering consumer products and services. It's a low-cost brand, and therefore doesn't qualify for excellent customer service, as does XS4ALL.
The InternetPlusBellen double play causes a flurry of complaints, but KPN has no intention of dropping the fee. They are extending the staffing though.