How to choose a best dissertation writing company?

I am a PhD student, and I have to complete a dissertation on July 10th. I have tried a lot but failed to complete a good dissertation. Now I am sure that I cannot complete it within remaining days. Thus I decided to choose a dissertation writing service. I need your help because it is very difficult to find out a genuine dissertation writing service. My friends were cheated by some scam dissertation writing services and they are helpless to suggest a genuine writing company. Please help me to find a genuine writing company.