Rat urine in ceiling

Hi forumers,
Seeking advice on a rodent issue in my roof.
I have recently moved in to a place and discovered there are rats having a party in the roof.
Several different types of bait have been used, ultrasonic units and gas traps and the little buggers are getting kfc from somewhere and taking it up there and skipping past all my efforts.

***My issue is the smell of urine from inside the house which I believe is from it soaking into the ceiling.
The house is relatively new, very clean otherwise and I never leave any food scraps about.

Anyone had this issue or had to replace the ceiling and/or roof bats?
It’s becoming quite overwhelming and I just don’t know where to start.

Thanks in advance