My neighbours are building a loft extension and as part of this have started to add to the Party Wall (currently an additional 4 bricks high, but I imagine will be more).
Should they have consulted me under the Party Wall Act before they started this work ?
You should have been served with a party wall notice 2 months before work commenced. It is likely that as well as raising the party wall they will be cutting pockets in it to insert beams.
You should ask them to cease work and serve the required notice.