Gst using by someone

A registered GST taxpayer is encountering an issue where their GST number is showing as already registered when attempting to sign up as a seller on Flipkart. They are seeking advice on where to complain or if an FIR is appropriate. Suggestions include checking registration dates with Flipkart, contacting the local GST department, verifying turnover via Income Tax 26AS, and checking GST portal credentials and filed returns. Engaging a consultant is also recommended for complex verification, with a note that separate GST registration might be needed for e-commerce operators.