Feel compelled to reply here...
If this report / system is truly valuable to your organization, do yourself a favor and don't try to cut corners. If the person who wrote the thing was fired, it would suggest they weren't looked on as particularly valuable, which raises questions about what someone trying to fix the thing might be walking into.
What makes a pro a pro is the fact that they have experience walking into disasters with little need for hand holding or explanation. If nobody knows how it works, there will be little information to go on. People you can hire to write code can be "cheap" because it's easy to bang on a keyboard and make stuff happen. Real software people are expensive, and there are many good reasons for that.
If you aren't software engineering-savvy, it will be very difficult for you to tell who knows what they're doing and who doesn't. The easiest way around this problem is to hire someone with a track record. My first suggestion would be to be wary of anyone who tells you it doesn't sound that hard. Nothing ever sounds complicated when a customer initially describes what they want, and this includes the synopsis you provided. There are always details. Always. Maybe you have found the one program that really is basic with almost no complexity, but if that was truly the case it would also have little value.
"A bunch of tables cross referenced and aggregated into reports" summarizes basically every useful piece of software in the business world. SAP is a bunch of tables cross referenced for reports. Tread carefully, IMO.