Jim -You may not be able to afford a lawyer/solicitor at the moment but surely your union can? Most unions have their own legal advisors and since your employer is using it's legal resources against you, are you not entitled to legal representation from the union? Someone suggested involving the newspapers, very risky but they, like the unions, have deep pockets too.
Sounds an awful lot like some irritating little nit in the IT department is out to make a name for themselves and has picked you.