Given a travel related situation, and given a specific question about the situation, summarize the question into a title

I recently applied for a short-term student visa, mentioning the departure and return dates as 13/05/18 and 10/08/18 (=90 days) respectively. After my visa got approved, the validity dates mentioned were 11/05/18 and 08/08/18 (=90 days) but since I have already booked my return flight on 10/08/18 and if I return back from France on 10//08/18 I'll be violating the visa policy. 

What will be the best thing which I can do in this scenario? 

If I go with this visa and violate the visa policy by exceeding the visa's validity by 2 days what consequences can I possibly face, considering the face that it wasn't actually my fault but a sheer mistake committed by people in embassy?

Can I stay in France more than the validity range of my Schengen visa given I'm not exceeding my duration limit?