Screws on the particulate filter

Dear Forum, today the message “Emission – Workshop” came at about 170tkm. I suspect my particle filter closes slowly. So it is removed. In the direction of travel it is fixed with three screws, one of which was torn off (right in the picture) although I bought the Phaeton 4Motion 3D from the VW dealer first hand. Well, sponge about it. Incredibly I got the remaining 2 extremely rusted nuts down without making them round. However, I get the sh I didn’t want to use too much violence at first and rather ask in the forum: Those depicted on the photo can only be stuck or was there something welded/pressed? Simple hammering doesn’t drive them out. If someone has done it before: Is it expensive to exchange the rubber hoses for the preliminary or the reprint at the same time? Where do they lead and is the fuzzy? Thank you and many greetings, Thomas