A too-little-too-late piece of advice: Home warranties are not worth jack. I am astonished by how much money they make for the companies. And I have been suckered in multiple times myself. Never again.
It is really unpleasant to contemplate, but you ought to re-pipe in the attic (assuming you are in a single story). Furthermore, do it right; this is plumbing that will be there for the remaining life of the house. Also, it involves tearing apart walls to access the bibbs; don’t settle for lousy drywall work.
Sorry for your predicament. Again, ouch; I feel your pain.
