Well, well, well; I have received my refund!!!
The person who mediated says that he has seen the proof of postage; though I haven't; however, I've no reason to doubt his word. In light of that, my comments about the seller posting it to himself appear to be factually incorrect, though I am still perplexed as to why I wasn't and still haven't been directly given that information.
I think it may be appropriate now to take down this thread, but before doing so, I would like to thanks the folks here for their support; I am sure that it wouldn't have happened without your help.