somewhere on here there is a link to an article about puppies and biting - it explains it is a process they have to go through, as it is by 'play' biting as a pup that they learn how much force not to use on us wimpy humans...
just persevere with ignoring, and yelping - albas oil put mine off chewing things they shouldn't too...
and if that doesn't work, you could wear doc martins or wellies until the phase passes!
Good luck!