I have managed to get them now. When you get them they are helpfull. Its a pitty they havent kept up with the cahnging world by at least responding to e-mails or even better making their webb site upto date.
I have a sterling 30A battery charger which is excellent. I rang up and spoke to CHarles Sterling himself who was very helpful.
I have an Adverc alternator controller which is superb and so are the chaps at Adverc - they are unfailingly helpful and knowledgable. I regard their product as superior and, as they make it themselves rather than import it, they know it backwards.
However tecnically minded you are, when you try and fit one of these things, you will be glad to be able to ring up and get an answer from someone who knows their product/