If it's at the dealer, escalate to the service manager and if he/she won't take responsibility, move on to BMW Canada (I am familiar with BMW USA, I assume you have an equivalent).

But, I feel like we are missing part of the story. How did you get from scored cylinders and a new engine to valve seals?

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David.X5
2001 X5 4.4i Sport
SOLD! at 160k miles