Cornflake, I am so sorry that this has not been resolved. Have you been told what the meeting is about? That should determine what you do next, ask for it in writing. If it it is a general chat then fine but if it strays into the regions of competency or disciplinary, leave. Explain that you are not happy to attend a meeting without the support of a colleague or your union representative as set out in the relevant policy. You can mutter about how disappointing it is when HR procedures are being adhered to as you leave. I am sure that you are a Union member but it might also be sensible to check your bank account or insurance to see if you have legal cover. Also if your Authority has an Employee Assistance Programme use the bejasus out of it for legal support and personal support.