At last! Managed to find time to seek another dealer - rea group croydon refused by saying keycards are only covered for 6 months.
(similar scenario with the 3rd brake light, was told it needed a new unit when in actual fact it just needed a bulb!)
Visited Davis of Sevenoaks today and am now awaiting the arrival of a new keycard - covered under the 60000 mile/3Year warranty. No 'bovine defecation' just plain speak.
Happy chappy now, will be able to lock the car with the card instead of pressing the central locking button for 5 secs, checking the card is in hand, exit car, close door