Original BMW parts???

[ZORISLAV]

I recently purchased an original BMW exhaust pipes and I am very disappointed. After a week day, black color within the exhaust pipes started to peel. I immediately reported problem to the authorized service and they have ordered a new exhaust pipes, but it happened the same after a week. Of course I have asked again new exhaust pipes but this time they sad to me that they are not sure that this is their problem because is already the second time happening. I have friend who was at the same time in the same service purchased exhaust pipes for 3.0d like me, and it is not happening. Whatever I am interested if someone has a similar problem with original BMW exhaust pipes