A publisher often divides itself up into imprints, which have varying degrees of autonomy. They do this to make it easier for themselves and for readers and bookshops, – because an imprint deals with a particular type of book.

For example, Harper Collins has the Voyager imprint and that specialises in fantasy and science fiction. So anyone buying a Voyager book knows what they are getting. Some publishers have lots of imprints – romance, sf, literary, chuildren's, young adult etc.

So Havenstar was published by an imprint (Virgin Worlds) which specialised in sf/f, part of the larger Virgin Publishing. It must have had internal problems because there was a quick turnover of editors. Anyway it wasn't a success and lasted less than a year. They took their stock and sold them dirt cheap I don't know where. And that was that.The books were unobtainable. As I said, they were on the top bestselling 100 Amazon titles one day, and unobtainable the next.

Perhaps some obscure bookstore somewhere had a 100 copies, but who knows…
Remaindering can also mean that they were destroyed.