1.6 HDi 2004 307sw

Ah, the common radiator fan problem that never stops running even with the
keys out (until the battery is dead). I am told that this is well known and
common on the 307 1.6 engine - the cat is right behind the radiator so
doesn't get the air flow that it should causing the fan to keep going. "It
SHOULD keep going but there is a setting in the relay that cuts it out when
the battery gets to low." The bullsh*t explanation from my Peugeot dealer as
I had the relay replaced to the newer type that "allows this to happen". 5
minutes down the road, exactly the same problem but I take their word for it
and let the fan run. It runs until the battery is dead! Before anybody tells
me that the battery is faulty, it isn't.

I have had changed both the fast and slow running fan relay (?) and the
problem is still exactly the same. I have read somewhere that a software
download will cure the problem. Is this true? What does it cost? Shouldn't
Peugeot do this for free?

Is the 2004 407sw 1.6 HDi the same engine as the 2004 307sw HDi?

Any knowledgeable suggestions would be greatly received.