If you told them that in advance then that certainly goes in your favour.
At the end of the day, they can probably just shrug their shoulders and tell you to take it up with the contractors that did the roof.
Unfortunately roofing contractors aren't the easiest of people to sort out as I've found out on a number of occasions.
In a time of universal deceit - telling the truth is a revolutionary act. George Orwell
When the debate is lost, slander becomes the tool of the loser. Socrates