De Volkskrant writes this.
According to a CZ spokesperson, the error was made when assessing oral care treatments for people who had taken out additional insurance for this purpose. They were reimbursed for more for a single procedure or multiple treatments than was covered by their policy. CZ reclaims the excess money from the insured.
CZ and dental treatments
This concerns coverage for dental treatments that were the result of an accident. In some cases, CZ also paid the practitioner for procedures that were not related to an accident.