I panicked when reading these reviews. However, I messaged them using the online form, also emailed them at *******@usenet.nl and called the UK number from their site (available in the contact hotline page). I wanted to cover all the possibilities. After the phone call my account was cancelled. Also received an email response to my cancellation request stating it had already been done. So no issues with cancellation. I did cancel well within the free trial period and not afterwards.
That being said, the service I believe gives false results on a Google search. I was searching for a specific book which usenet.nl said they had so signed up. The book was nowhere to be found, hence the cancellation.
There are better usenet services by far.