DPF Soot level display

[BlackC55]

Whilst you're on the subject of soot, I'm wondering if someone can help me. I'm very new to forums!
My lad has an A180d 2017, it had a slight whistling noise intermittently, now it's a little more regular, it's coming from the rear of the engine and the area is covered in soot, I presume gas (exhaust fumes) escaping from somewhere?
Can anyone help of has experience with this issue?
Cheers

You need a new rear section exhaust. The exhaust flap is seized.