24-04-2021 2:39 PM
You are pehaps unlucky. In the whole of the last year I have bought lots from eBay and not one has been later than the advertised last date. Most arrive on the next day [24 hour] or the day after [48 hour]. There is no general delay to Royal Mail. My eBay purchase this week turned up on time
My regular Wednesday purchase [not eBay] arrived every single time on the day.
If something is still outstanding on the latest date for delivery then open a "non-receipt" case straight away to flag it to the seller and to eBay