Hey Reena, I used them for a dissertation on political science once and they delivered me a good one, so now I'm a PhD holder. Not really sure if they can do a good job on a paper with a different subject, I only ordered political science papers. But one of my friends who also uses them right now for business studies, says that the papers are awesome.
I think if you are worried about your dissertation, it is better to call them and to talk on the phone because every paper is unique and only when you walk them through all the details they will be able to tell you for sure if they can do that or not, how long it will take, etc.
So, good luck!