If these bugs and additions are little things that need to be taken care of, I am the man for the job!
If I can't finish the project by the proposed time, you do not have to pay me anything whatsoever!
I have been using Unity for 2 years now, and have been modding games for nearly 17 years.
If I can't finish your bug fixes and a few little things you want added, then you don't have to pay me anything whatsoever and still get all the work I have completed absolutely free.
I am doing this, because I believe in a good business ethic, you expect something to get done, and I would be the same way as well!
Hope to hear from you soon!
Thank you.