Without seeing a copy of the solution, etc. hard to say. We have no idea how your old staff wrote their script, or where, etc. Sounds like you need someone on-site to fix this issue for you.
The C drive letter would appear to indicate a drive that is local to the current user and not on a server somewhere.
You might also double check to make sure that the script you are examining is really the script that is importing your data and that some other script with a different file reference to a different location is doing the actual import.