Help needed on detecting software errors
You need to set up a separate testing unit that can regularly assess the software modules for any errors. If you already have a testing unit, then you need to bend the way it is working. As you said the errors in software modules are being detected late which leads to complete reformation of the module. I would suggest you to make the testing team work in parallel with the development team as soon as the product coding begin so that the test team can detect the errors at each stage of development and those can be fixed on that very stage which will make the final product bug free.
There is a free open source software, JAVA Pathfinder, release by NASA to the public for free.
This was used by NASA on its six wheeled solar powered rover to detect inconsistencies.
NASA released this to also get a feedback from the public for further improvement.
According to NASA, this had been enhanced and tested by the educational institution and some companies.
I likewise found at AMAZON a kindle edition publication, Software Defect Detection Techniques – Tips to Stop Bugging!, you may also want to look into for your company.
You were querying for an IT expert to help you, get referrals from where you purchased your units.
This is your best course of action to start.