I've been on freeserve for ages, on the off peak deal. All fine until a couple of weeks ago when I couldn't connect for about 3 days. Rang them and discovered that for new members they have a new off peak freephone number, which existing customers may also use.
So if you are having trouble getting through on 0844 040 2001
Try changing the number to 0844 040 4951.
Its really easy to do, just change it in the properties section.
Since then I had one problem using the old number, tried the new, and connected straight away.
So there's a good tip for you all.