I have little knowledge of cars. Last July i bought 2010 Ford Fiesta with a low genuine mileage from a reputable main ford dealer with a 12 months warranty. After a few months i found that the brakes "were slow to react". Brought car back to dealer s who agreed there was a problem. They mentioned something about bleeding the system and at the time after getting the car back the brakes were ok for some weeks. The same problem arose again and i brought it back and was told they had sorted the problem by some computer method. However they said it it arose again to contact them before the warranty expired which would seem to suggest that some material replacement might be necessary. Is this a common occurrence and any advice woould be appreciated