I agree with Woodsmith, there are too many imponderables to answer with any certainty.
It's not in itself a difficult or time-consuming job, about half a day's work for a "simple" replacement, but much will depend on what's found when you're up there.
And as said, it depends on whether the job was done the "cheap" way with a ladder to the eaves and a cat-ladder to the ridge...
http://www.midlandladders.com/products/Lyte_Double_3_0m_Extending_Trade_Roof_Lad......or (to keep Health & Safety happy) the expensive way with scaffolding.
Even if it was just a half day's job, I doubt many guys would bother turning out without charging for a full day to cover travel and the fact that it's spoiled a full day's job somewhere else.