Buyer purchased an item under $10 - we shipped using Amazon's USPS Standard Shipping Envelope service, which is untracked. Buyer contacted us that item wasn't received. We reply to buyer asking if they want replacement or refund. Buyer never replies, but instead opens atoz. I appealed, stating buyer is entitled to a refund but the atoz should not be a defect on our ODR because we were waiting for the buyer to choose refund or replacement. The appeal was denied. Can anyone offer advice on getting atoz's like this reversed?