As far as your first point is concerned I really do think you are being very hard on yourself. Surely teachers are meant to be reasonably intelligent individuals and are able to read. Finding out about Threshold rules is not at all difficult for anybody. The point I am trying to make is that the individual teacher has a certain responsibility to make themselves aware of the rules. As far as your second point is concerned, I would contact your union at ( at least) regional level for further advice.