Airfix and Heller are completely separate entities.
Heller went bust a couple of years ago - last time I looked, they were going through the French equivalent of Chapter 11. The time period permitted for them to find new buyers/backers expired some time ago and I haven't heard anything since.There is a law similar to the US law under which a company can call on legal administration and get its debt frozen for 6 months (ending January 20th 2007 for Heller). During this time the company had to prove to the judges that it was a viable business and that it could pay its debtors (albeit in the future). The court had to validate business management and continuity each two months.
If no one came forward to inject new funds into Heller then at the end of January it will have gone from "legal administration" to "legal dissolution" where the judge will have sold bits and parts of anything he/she could find (tooling , goods, machinery, real estate, patents etc...) to cover the debts incurred by the company.
Let's hope for Heller they won't come to such extremities as it would mean death of the company (but someone could buy the name)
After Hornby took over Airfix, they had all of the old Airfix moulds shipped back to the UK from Heller's plant in Trun.
The Airfix 4 stackers are indeed repops of the Mirage kits.
The 1/400 KGV/POW & Hood, along with the Scharnhorst/Gneisenhau kits are ex-Heller and reboxed by Airfix.
At the beginning of 2007, Heller announced a 'New Release' list which never materialized.
The list included the likes of their long OOP 1/400 Jean Bart, Richelieu, and Strasburg 1/400 kits.
(Scroll down to the bottom for ships)
http://modelstories.free.fr/news/News07_HELR_P/index.html
I have heard nothing more about the fate of Heller since then.