Refund for Dropbox charge

I recently changed jobs and my new job does not utilize Dropbox.   Needing to subscribe to a new software system, I transferred all my files and then went to account settings and downgraded my plan from Business to Basic.  This past September (almost a year later) Dropbox charged me $158.88 for that basic plan.  The charge went through automatically via PayPal which is  the billing method I used when I was a paying subscriber.  

Beyond this billing error on Dropbox's behalf, a major problem is that once a customer downgrades to a Basic Plan, you have zero customer service and no access to Billing Settings to prevent this error happening again.  I have sent multiple emails to Dropbox, PayPal and my bank, protesting the charge.  The only response I can get from Dropbox is through their Sales team, which of course, cannot help me.  They send me back to Billing, whom I never hear from.

 I'm hoping that someone in the community can help with this issue.  I have always found their product to be good and have used it (at Business level subscription) for years.  I'd rather not part ways with such a bad taste in my mouth.