The RDW is the competent authority which is designated by the minister of LNV.
It is possible to check the certificate. This application will show you the information stated on the certificate. You can check the information against the certificate to confirm the authenticity of the certificate.
The VWA is still the authority which provides the Transporter authorisation etc. Any questions about this go to the VWA-site. The VWA is also the authority to re-draw the certificate of approval in case the means of transport not comply with the requirements in the council regulation.