I can't cancel my Adobe Stock subscription

Hello, I was hoping someone could help me. 

I used Adobe Stock for a school assignment, it was the free trial. It was of good use, but knowing myself, I would never use it again so I cancelled the free trial. Somewhat a month later, I get a bill saying that I have to pay €36 for something I used on Adobe. I was dumbfounded and clueless because I never agreed to any subscription, I didn't even get any clue of what Adobe program I might have used that made this bill happen. I tried calling customer service a couple of times, but it didn't recognize the number, I tried e-mailing, but it wouldn't allow me to send an e-mail for whatever reason. On the billing, it said nothing about an annual subscription so I thought it might have been a one time thing, so I just decided to pay it and to put it behind me. I also went on PayPal and I saw that Adobe was in my automatic payments list, which I found really weird so I put it in my inactive list. I thought everything was okay again, turns out it wasn't. 

Less than an hour ago, I received an e-mail from Adobe stating that I didn't pay my bill for this month AND that I had an annual subscription for Adobe Stock for 10 assets a month. I couldn't believe my eyes, because I had clearly cancelled the free trial and now this? So I go on my Adobe account to my subscriptions, I see that I have one for Adobe Stock and I got pissed to be honest. So I go out of my way to try and cancel it, but it was impossible. 

I feel scammed and as I'm still a student from a struggling family I don't have the money to be paying €36+ a month for something I didn't sign up for and will NEVER use.

I hope someone can help me with this.