Billing issues after trial options.

Hi, I'm Ellie. I'm writing to fix my billing issues on my trial option of PDF Pro. I have known that my trial cycle would be validated until today. So I cancel my trial option this morning, but I found that the ADOBE already charged a montly fee ($21.24) to me although the free cycle has not yet ended. So I would like to cancel my regular subscription and I'm looking forward to getting refund from the ADOBE. Could you help me solve this issue? I don't want to subscribe to this service now. I'm looking forward to hearing back from you. 🙂