Yeah, this is a scenario where you only real hope is to obtain the original. Even if at cost. The scan can only be fixed to a point and... it won't be much good any way you do it. Scanners are tricky. You've got to have a good one to start, and then know how to work the software right to get a decent copy, and then you've still got to be a photoshop wizz to fix the remaining elements.
As it is... get a hold of that hard copy. It's your only hope.
With a good scanner, that you know how to work well, and photoshop skills to boot, you can sometimes come out ahead: