[mothered]

A courier just appeared at my door asking if I had a pair of sunglasses to return, I played dumb and acted like I had no idea what he was talking about, was that the right thing to do?

Absolutely.

The carrier has no right to set foot on your property demanding answers for a claim that has already been handled and finalized by the company.

Oakley haven't sent me any emails to say that someone would be coming or that anything needed to be returned, so why should I give the courier anything.

Even If Oakley did request a return, they can Issue the return label.

You've EB'd them (and not DNA'd), so I don't understand why the carrier Is getting Involved.