Hi. I'm new here, so go easy

I've got an Audi A3 8L1 2003 1.9tdi. I'm having the rear brakes serviced next Saturday but I'm getting the parts. I want to renew the brake disk shield, behind the brake disks as well, but can't find the parts, or a part number anywhere.

I looked in my Haynes manual and can only see the part described as brake shields. It's like the housing that sits behind the brake disk.

I'd really appreciate if someone could help me find out what the part number might be.

Many thanks.

Gaz