crows on roof

This is my first post so, hope I'm doing it right...

For a few weeks now I have had Crows running around my roof, making loud tapping noises as they walk. It's much louder than you'd think and they are waking me up each morning. Now I'm pretty certain they are pecking as well which is even louder!

Any advice into how to perhaps deter them? I live in a flat, in the roof section!