I've not had to deal with this specific issue ( yet...) but have got out of warranty experience of Citroen when the clutch on our manual C4 Picasso failed at 47k and 9 months out of warranty - the fault was diagnosed as the clutch release bearing suffering complete mechanical failure. Despite being out of warranty Citroen paid 100% of the cost which I put down to three things;
1) It was clearly not an issue of how the car was driven
2) My dealer, Duxford Motor Group, work hard for their customers and it is very clear from discussions I've had with other Citroen owners that the success of a warranty claim is heavily dependant upon the efforts put by the submitting dealer
3) The dealer explained to me he first two questions they always ask on an out of warranty is a) how loyal to the dealership are they and how loyal to Citroen - bought and maintained at the dealer is gold, maintained at the dealer is the next best thing. Our car was used, bought from a main dealer and always looked after by Duxford.
Even they were amazed the whole cost was paid by Citroen - they expected a contribution of some nature and suggested it was probably a known issue. However, a FCSH clearly helps. I've also had two replacement seat bases on the picasso (a known issue of the outside bolster collapsing that affects most of them) the first one was done under warranty which they extended to a full claim for 5 years or 60k or part claim after - sadly I only noticed it the second time at 3 months short of 5 years but on 63k; we paid for the part (£93) and Citroen paid the labour (£300...) so Citroen do support known issues outside of warranty so I'd suspect your car will be covered as this is clearly a known issue (even if they haven't formally extended the warranty)
My advice is approach your dealer and be friendly with them - it works a treat on my opinion where as my Dad has a lousy relationship with his Honda dealer as his approach is always 'you have inconvenienced me and you are the problem' it's not the way to make friends...
One thing that is worth knowing which Duxford explained - if the customer makes a contribution of some sort then a warranty applies to the item (2 years in the cars of Citroen repairs I believe) where as if there's no contribution a warranty does not exist - in the case of our second seat base it had a 2 year warranty, in the case of the clutch apart from any moral obligations, the moment I picked the car up there was no warranty on the repair.
