Problem with an unknown film provider?

Yesterday I received an e-mail requesting payment of a sum for my "premium account" from a film provider I never heard of and whose side I was never on. (Why, even if I already have Netflix).

I checked my progress and found that I had never visited the site and I did not have any email traffic with the site before, there was neither a registration confirmation nor anything else in the form.

I'm now wondering what to do, the e-mail mentioned that if payment was not received, the information will be passed on to their lawyer.

Is there any way a solution to the problem? The amount is not really low now, 30 euro a month and the "contract" is valid for the whole year, is even more expensive than Netflix and it is also something so unknown.

The provider is goldflix.de

Look here:

https://www.mimikama.at/allgemein/kinofilm-streaming/

I have the same problem.