If the broadband works OK, chances are the problem is at your end. Unplug everything, including filters, and plug in one at a time into one socket. Do the same at the next socket. A pattern may emerge of which socket, filter or phone is putting the noise on. I found one phone in the bedroom put noise on when it was just plugged in, so I leave it unplugged!
You should not have to 'put up' with the noise, but be aware if a BT engineer attends, and proves the line OK, you will get a hefty bill.