anchor — Rate more than mrp without gst bill

I have purchased electrical wiring fittings (anchor brand) from a vendor (mr. Rajiv, address- vpo- ghorghat, ps- bariyarpur, dist- munger, bihar, pin- 811211, mobile no. [protected]). The vendor is charging more than the displayed mrp & not providing gst bill. That vendor is demanding additional money to provide gst bill.
Even a district level distributor (mahaveer electricals, munger, mob no. [protected]) also not providing gst bill & demanding additional charge for gst bill.
Kindly look into the matter that how anchor can authorise such vendors to deal without gst registration & taking fancy prices illegally.
Thnx