Sadly the days of BMW exhausts out lasting the cars are long gone. Exhaust is essentially a service item. The location of the back box means that it will get a pounding by the elements. I'm looking forward to mine going, so I have an excuse to buy a custom performance cat back system
I believe there is some come back with the finance company. Its worth talking to them and see what they say. I know others who have worked things out with the finance company when they have similar problems.