DROPBOX CANCELLED BUT STILL BEING BILLED

I enjoy using Dropbox. BUT I needed to CANCEL MY SUBSCRIPTION due to my financial circumstances. I downgraded to the FREE basic plan in June last year but I AM STILL BEING DEBITED R199 EVERY MONTH! The Dropbox help function is close to non-existent. I am SO frustrated! I am paying money every month for NOTHING! I want it stopped and I want a refund! Any ideas?