It certainly seems odd that they recognise a problem, but then won't fix it!!
My advice would be to speak to one of these "Free for the first half hour" solicitors to register that there is a problem with your car and then if it does fail outside warranty and they won't fix it etc. you can then quote the sales of goods act that the car isn't "fit for purpose" and they were informed of the problem but failed to act on it.
If it's a common problem which affects different models, then it's obviously a design fault which they should fix.
Hopefully it won't come to that!!
If it ain't broke, fix it 'til it is!