If you log in to eBay.com instead of eBay.co.uk there is a useful little tool in the top right corner called "Live Help" that UK eBay customers generally don't know about -
It can be very useful as an alternative to the automated e-mail replies if you need to ask a question.
Now if LOTS of their customers used this facility to ask your Sign In question,
eBay might just get the message and do something about it
Coconutty