House not winterized properly after inspection. Who pays repair?

[Craig March]

Purchased an investor owned property. They had it dewinterized for our HUD inspection for a renovation mortgage. All plumbing worked without issue

They had it rewinteized on 12/11/18 a week after our inspection. We didn’t close until 2/27/19. Today (3/13/19) I had plumbers out to install a new hot water tank that was missing and to dewinterize the property. They noticed one cracked pipe at a low spot in the house and repaired. Once water was turned back on they found and repaired roughly 15 splits in the pipes from the second floor to the basement between the hot and cold lines. Ceilings were taken down, walls were cut open and water obviously got into everything. 

Question is, who should be responsible for the bill? House was purchased “as is” but the condition has changed and those repairs for the pipes are not budgeted in the mortgage. 

I have already spoken to the insurance company who is doubting coverage since the damage most likely occurred prior to my policy from improper winterization.

Also spoke with lawyer who is doubting we would be able to prove fraud or negligence against the seller. 

Both options leave me with the bill which I just can’t accept. Any advice?