There's a replacement 'loom-end' available - socket to bare-ended wires - and the fix is to cut off the original melted socket & splice the new loom-end onto the original wires. Parts are on order - http://www.heaterblowerresistor.co.uk/peugeot206307heaterresistor.html
Trouble is - the original loom is so short that getting my conventional ratchet crimp up behind the dashboard to make a decent crimp is going to be 'challenging'. Same would go for soldering.
I was wondering about the possible alternatives...? Choc-bloc / terminal block seems a bit of a bodge in a vibration-prone automotive environment, but would the Wago 221's be up to the job - I've never used them before?