PHP advanced support

We are looking for someone to help on a complex project. It is code that is not documented, very confusing and we had taken over from another developmentgroup. In the first step we want that the application comes up. It works locally and works on a living site, but in the online testenvironment we get some problems. We would ask to find out what is happening. Normally it must work, we think there are some hidden settings etc. If you can fix it, then it is a sign that we can work on a longer term