Can a company ignore my cancellation email?

Hi dear Lemmy / Netherlands people! I have a problem. On the 7-th of February, I've sent an email to a Dutch company. I've requested to cancel my paid subscription (dozens of euros per month). They are denying my cancellation saying I haven't gone to their (broken) website, and asking for 2 additional months of payment from me now.

Who is in the right here? Should I deny the incoming payment requests even if they threaten with debt collection services?

The email that I've sent originally was this:

Subject: Subscription cancellation

Good day,

I couldn't find an account management option on the website. Could you please cancel my MyHealthClub subscription?

( = not extend it for the next month)

My email is *****@gmail.com,

**** Month **

Thank you,

Name