I think Sir Rad found it for you... ;)
One of the worst (for different reasons) has to be Abbey National's , sorry, Abbey's. I've been using it for several years and it is not intuitive at all. You would expect Bank sites to be easy to use, but this has me tearing my hair out every time I log on.
Just one example of the hopeless programing: They don't seem to realize that a change of year comes about every January 1st, so if you have a few years of transactions, as I do, you can't see in what year each transaction took place, and you can't break them down into annual summaries. You would have thought that was pretty high on the list for inclusion!
I've had to call the Helpline on several occasions and the response is always:'Yes, we've had lots of complaints about that...' Aaahhhh!