Dear Swati,
Draft a policy on grievance handling get it approval from Top management & communicate to all workers/staff/managers.
In the complaint form,you have to fill on behalf of employee or help them and get them singnature,there should be policy that no one disclosed the name of the complainent except few top managers know the his/her name.
You should put suggestion box/arrange complaint register where they can drop their complaint and after every 15 days ,the drop box to be opened by the authorised person then get enquiry on this,monitor the issues,call to the complainant & ask the incident/issue on details then analyse & take appropriate action.
Best Regards
Sajid Ansari-Delhi
there should be few top management invo