Bajaj Auto — Vehicle registration number not giving

I bought bajaj ns 125 motorcycle from bazaar showroom last 20.01.22 with cash 125260 rupees. But the showroom still did not give me any vehicle number plate or any other kind of documents.

My vehicle details
MODEL- NS125
CHASIS NO- MD2B72BX8MCH04460
ENGINE NO- JEXCMH52331

MY CONTACT DETAILS
HASIBUL ISLAM
[protected] / [protected]
[protected]@gmail.com
Nutangram
Belai
Birbhum
West Bengal
731215