I received my lens back this am from Zeiss.
It has been upgraded and appears to be working properly - at last and not even an apology!
I'm still awaiting the refund of my not inconsiderable costs in returning the lens to Zeiss in Germany from the UK.
In Malta, diving with H2O, I was forbidden to use strobe when photographing a seahorse. Apparently it can damage their eyesight to the point of putting life at risk, so I'm fine to hike up the ISO and shoot natural light. As a good citizen of the oceans, I follow this rule outside of Malta too. http://flic.kr/p/nyqQR9