This was fantastically creepy. <-- That is supposed to be a compliment.
I love that you made her find little things from her father and brother- it made it feel much more real.
The focus on the man's tattoos, the blackness (both inside the tunnels and of their robes) was perfect- it never became too much.
I also love how you kept going back to the time and reception of the phone. The fact that even after her phone had died, she kept it with her also showed how real the character was- I know that that's exactly what I would do. Even when I have my phone off for days, I like to keep it with me- it makes me feel better than if I don't have it.