Finally able to report back on my experience with STC; there was an issue, but the story has a happy ending!
l received one of the decants l ordered after just one week, (very fast to the UK!) but after a month was still awaiting the remainder. l emailed them, & received a prompt & very apologetic reply. Because their orders are sent from more than one source, (as are TPC's orders) the second part of my order had accidentally been marked as sent. This had apparently happened to other orders but been spotted; it seems mine had not.
They offered me a choice of $10 off my next order, or a couple of "extras" of my choice; l chose the extras. This was around 10 days ago, & l just received my package today. The decants & samples are nicely packaged in a little box, & everything is in order.
ln summary, l am very pleased with the swift & generous response to my problem, & would highly recommend their service to anyone. As is often the case, polite communication goes a long way to achieving a good outcome.