we are bmw drivers from 1997-no help now.

We are BMW drivers from 1997.Always we have 2 or 3-4 bmw's in our garage.Last one we brought november 2008,530 d sport.We serviced that one always on Cedar Isle dealership.For the past 3 years we have lodge so many times complain that something is wrong with battery.We brought car in after email call that all owners bring that seria for check up.They change battery.Our car has a huge battery leak in the boot and was acrid smell.Some reachable part of electrical installation was also replaced as it was completely burnt and melted and black.Some time after that all was ok but then it starts showing battery sign on display,signalization was on -off working and every time we are in for service we give complain and telephonically many times to a lady manager at Cedar Isle.Signalization is now working only partially.On last service in august 2015.we lodge new complain but record of our complains ,,does not exist;"investigation""from Head office but we are turned off-no help.Its "