Charges to my account when the subscription ends

Not sure who I should talk to. I have a subscription with Duolingo I need to know when it expires because I do not want it renewed. I really didn’t want apple to add it. No one asked me if I wanted to add one year subscription. I was going to keep using dúo for free. Anyways when I got notice that I was charged a yearly subscription I decided to keep it for the year BUT I’m not wanting to renew when subscription ends. What do I have to do for apple not to renew Duolingo.

I tried calling Apple but can’t seem to get the phone to ring. Any suggestions??

Thank you , Diane Patton

PS. I USE MY I PAD WHEN DOING DUOLINGO