Isn't the whole point to do it yourself though?
I see it as a good pre-cursor to whether you are suitable for further study such as a masters which is more self driven academic study.
Do you mean helping with the essentials such as how to plan, research, set out, bibliograph sources properly etc... or with the subject matter itself?
There is such a variety though between subject such as law like mine, arts, sciences etc...
I wouldn't pay for a dissertation, I did my own. It's a pointless exercise if you don't do it yourself.