Hi Adobe, Please help me with this

I want a refund of the last invoice. I already cancelled than trial right after I used it. I started the free trial at Dec 1 and cancelled it on the same day (dec 1). Received the confirmation that I cancelled everthing and now I got charge for a month payment and yet there's no "manage plan" to cancel it because YES I cancelled it a minute I started the free trial. how can I get my money back?