Joomla and SEF Components Expert

Project Description:
I need someone to help me with the issue on my website but I have low budget for the job. I'd like someone who is:
-Familiar with Joomla development
-Familiar with Joomla Extensions SEF components
-Good knowledge in Google crawl errors
-Do not take up front payment until the job is completed to satisfaction
-Confident that the job can be completed
-Familiar with Nginx server

I have increasing Google crawl errors which is caused by SEF rewriting. I use AceSEF but Joomla Core SEF rules seem to be active at the same time. Also, it seems I have 2 versions of my website active at the same time in my server because my designer left a copy of his testing site in my server. Some people have suggested to change my SEF components to SH404sef. If you think this can also solve the problem, please quote sensibly for:

1. Deactivate one version of my site, make sure only one version is active only.
2. Redirect all visitors to the other version/one version only
2. Configure SH404sef for my server Nginx - It will be better if you have a copy for testing because my current SEF is a paid component. I don't mind buying SH404sef if it can work to solve the issue.
3. Disable all other SEF rewriting.
4. Solve the Google crawl errors

I'll release your payment if I can see the errors continue to reduce. Please propose with total hours it will take you to fix it. I don't mind to adjust my hourly rate if you are really good at this job.