It may also be worth checking Adrian's thread on a similar subject - problem sorted by Darren at New Elms. If its warped discs, talk to Colin (Spanner Juggler) - have the old ones skimmed, new ones will only go the same way...
Graham (G4FUJ)
Sold L44FOR 4/4 Giallo Fly '11 MINI Countryman Cooper D All4 '90 LR 90 SW