I have at last got the problem of the DSC NOT AVAILABLE problem. Last week I put my foot on the brake and found it to be rather hard to put any pressure on it and when I drove into my driveway, which on a decline I had difficulty stopping the car. I called the RAC who diagnosed a faulty Brake Servo, I therefore had to have the car taken to a local garage who quoted me about £800 to fix a new Brake servo. After some negotiation I found a used Servo on Ebay for £174.99 which was fitted and found out this fixed the problem and I do not have the warning light for DSC NOT AVAILABLE anymore. Hope this helps JDE