No brake pad wear sensor light on dash and had a loud screeching noise from front left wheel so immediately thought wheel bearing. On inspection I found the sensor totally mangled and hanging out. Looking through inspection hole it appeared that the inner was down to min.Off wheel out tool box only to find I didn't have a 7mm allen key socket. Once sourced off came the caliper and shock horror. The inside pad fell apart with basically only half of the lining left and totally detached from the metal mounting plate. The outer one was well above min. Cleaned everything up and replaced pads. Off with driver side and again pads were well above min. Only thing I can think of was a sticking piston. Smeared brake fluid around pistons on both sides ( under rubber sleeve) and copper slipped everything else ( not pads). All working fine now but will monitor over next month or so. Few things came to mind though, car is a 2004 and never had pads changed so wear rate is really good, wear sensor didn't work ? and dealers wanted £66 plus the vat. Local supplyer priced at £17 for pads and £10 for sensor. Same pads. Anybody else had this happen???