Exhaust Rattle on 2016 BMW X4 M40i

[Montreal911]

Hi all,

There's a rattle that comes from the driver's side muffler on my wife's X4 M40i. The noise was annoying and very loud while idling so my investigation narrowed it down to the driver side flap. I installed a clamp (as pointed on the picture) to make it stop rattling but the flap is always open now.

The BMW dealer says it's Part Number: 18308693961 which is the entire rear muffler that comes with the exhaust flap.

Question: anyone went through this before? is there a way to purchase/change just the flap?