Which Agencies Are Responsible For Consumer Protection In California, And Where Can I Report California-based Companies Engaging In Deceptive Billing Practices?

I'm a European who purchased a trial subscription at an online company based in California. I canceled the subscription before the trial period ended, thinking everything was fine. However, I later discovered that I was charged for an additional $39. After contacting customer support, they informed me that I had agreed to a bonus offer for an affiliated website. The problem is that the website had a white background with light grey text that was very small and nearly impossible to notice, even for me (a 25-year-old with perfect eyesight) unless it was specifically highlighted. The company eventually highlighted this text in bright red.

The affiliated company is based in the Netherlands, and I plan to report them(hound them unless they give me my money) to EU and Dutch consumer protection agencies for deceptive practices. However, I'm unsure about how to report this issue to US authorities, if that is even possible, as I’ve heard that consumer protection laws, even in progressive states like California, can be weak.