My certification in Google Webmaster tools as a full-time job, I'm a developer and understand how you might have uploaded these files by mistake. I will be able to provide a confident, quick response or give you your money back.
It's a pretty simple process to be honest, just time consuming, and important! You should also put in a 301 Redirect in the htaccess file for all the 404 error pages, this will help fix the issue as well. I can help with this too.