Hi Masrani,
You might want to consider Bronte College in Mississauga, a safe, more residential suburb of Toronto, but also just 20 minutes away from downtown Toronto. They are an AP boarding school with grades 9-12. Their fees are also quite reasonable. Tuition fees are CAD $10,200 - 12,800/grade and they also offer single rooms in the residence. Both their residence and cafeteria are open on holidays, which makes it super convenient for your daughter to stay and not have to find alternative accommodation (which is normal boarding school practice - students to have to vacate the premises during holidays and school breaks). Furthermore they are a good school, quite a lot of their grads go to U of T each year.
Good luck!