Thanks so much for the replies. So frustrating. From what we gather the glass is:
Toughened Double Glazed Slimite Sealed units with Low E coating.
The manufacturer is claiming this is normal which is crazy! BUT apparently the Glass Federation only label glass as defective if you can see distortions from head on, in diffused light, from 3 meters and from inside the house. So specific and to be honest its quite hard to see defections in this specific scenario.
We've spoken to some other manufactures who agree the distortion is excessive. Convincing the glass manfactuerer to replace them all seems unlikely and the cost to us would be huge! there are 200 panes.
AAAAHHHH
Thanks again for all the help