Adult Tube php script changes/fix

I bought an adult tube site script and have had nothing but problems with the company that sold it to me and installed it so I won't be hiring them to make any changes or do any further work. Currently, when I make changes such as changing the title and meta tags of the site via the backend and then click the submit button, I get a 404 error, so obviously there is something in the code that is messed up. I need that fixed. I will need the "layout" changed around a bit as well. In other words, I don't want it to resemble all the "other" tube sites that are using the same script. I will need certain parts of the script removed and maybe a couple things added. Of course I realize that a price cannot be put on the things that will be added because you don't know what will be added yet. Please let me know your fees and what you can do for me. Also let me know your experience. Inexperienced need not apply.