I recently took my 2000 E46 318 coupe to kwik fit for a brake check as my brake light switched on.
(i expected it to be just new pads required)
They told me that the main cyclinder needs replacing and all the fluid has leaked out causing damage. they suggested that all pads/discs (front/back) needed replacing as well as the main cyclinder itself..
it would have cost about £800 which i refused to pay and drove the car home...
is it common that all pads/discs need replacing if the fluid leaks completely??