Late delivery defects on untracked large letters.

I have two more late delivery defects on untracked large letters that are being scanned on delivery and showing as arriving late. I have brought this matter to your attention before but it remains unresolved. As they are untracked items when they are scanned as accepted at post office it does not appear on RM's system but RM are scanning them at delivery which if they are delivered late gives the seller a defect unfairly when the seller has a proof of posting to prove that the item was posted on time. 

When will ebay accept a post office proof of posting as evidence that the item was posted on time.

Imagine if a sellers late delivery rate went over the threshold and they were charged higher fees through no fault of their own. Would this scenario be acceptable? One could even think that it is in ebays interest to ignore proof of postings so they could charge higher fees!