Often, customers were able to select free shiping options, although not with any kind of apparent pattern. It was not price or location based. So to solve the issue, I disabled the free shipping options.

Now it will not allow customers to choose certain shipping options at all. The "choose shipping option" screen simply will not allow the customer any further. Can anyone suggest why this might be?

Also, the UK shipping prices changed recently. Where can I get the correct current module to cover this?