My 2006 Mazda 6 on a 55 plate is now spending its eighth week in a main dealer to sort out a problem with the brakes at low speed in first and reverse gear. It's now thought to be carbon deposits. I've had to authorise the dismantling of the engine as I felt I had no choice, as if I were to sell the car on I have to legally declare the fault and that the engine requires dismantling to determine the problem. I have been advised the warranty will cover component repairs, but not if its carbon deposits. I've also been advised that deposits may be due to poor maintenance (unlikely, as it has a full Mazda service history), or the wrong diesel (naively I didn't know there was a right one).

As I've only enjoyed the car since last August (when it was 3.5 years old) and added 13,000 miles to it, to say I'm disappointed would be an understatement. I bought the car because of the FSH and one previous owner, believing the hype that diesels are good for at least 200,000 miles. Its a fantastic car apart from this problem which will have rendered it almost unsaleable if not fixed. Can you help?