I love the S3 but I am honestly no good with cars. The warning light came on for brake pads earlier this evening and now I am worried about being out of pocket. Like I say, I am hopeless with the car so fitting etc is a no no. and even detecteing which ones are gone, whether it's the front or back (or both) would be a problem. Should it be necessary to do both the front and back brakes? Should I but the pads first and fit them later? Also, I want to know approximately how much this would cost to be done by Audi or another recommnded garage. Thank you.