Post Office turning away eBay sold packages

Another thread on post office's refusing packages that last week we were told by would not happen.
Yet it is. Apparently they have all these post offices been emailed that any marked with MARKET PLACE SELLER have to accepted regardless.
But there numerous reports they have never seen such an email.
Can you clarify who exactly is ebays contract with is royal mail or the post office? I suspect its with royal mail and not the post office who are a very large collection of independents. Who have been heavily fined for collecting mislabelled packages so you can see why they are refusing.
I am on first name terms with all at my local post office and they will refuse any mislabelled packages.
What up to date info do you have on this?

Another thread on post office's refusing packages that last week we were told by community-team@ebay  would not happen.
Yet it is. Apparently they have all these post offices been emailed that any marked with MARKET PLACE SELLER have to accepted regardless.
But there numerous reports they have never seen such an email.
Can you clarify who exactly is ebays contract with is royal mail or the post office? I suspect its with royal mail and not the post office who are a very large collection of independents. Who have been heavily fined for collecting mislabelled packages so you can see why they are refusing.
I am on first name terms with all at my local post office and they will refuse any mislabelled packages.
What up to date info do you have on this?