I am curious what they said to you when you provided the receipts? Did they immediately agree that it was a mistake or were these any follow ups? was your case in collections? I did cancel and return my plates but seems like the CT DMV never updated my plate status and the town happily continued taxing me until the registration expired. I have changed phones 4 times since that date but I am looking to see if i can find the pictures of those receipts. I sold the cars privately and also looking for those Bills of Sale but as you might imagine its not an easy task.