I rarely use the service but tried to log in today and it tells me that my device isn't registered (even though it is listed as one of my two devices). So I tried deleting it and registering it again. Still no luck. I was going to have another shot but it says I've used up my changes (of course I have, trying to get one of them to work!)
Thanks Kath, I'll try it again when I get home. However that is *exactly* what I did before: deleted and re-registered. It didn't work, so I tried it again, but which time I had used up the 'available devices' allowance of course. There is maybe a list of triggers that enable the website to reject a device as not recognised. If these were made known, it might make it easier to avoid them.