HP India — Not giving the hp offer voucher & cheating

Address:

Purba Medinipur, West Bengal, 721653

Yesterday i visit a nearest dealer which is situated in mecheda, purba medinipur, name as"hard & soft" (Hp world), to purchase a new laptop 15ay 514tx,
Before purchasing this shop keeper promised to give a offer after paying 999rs, i was ready to pay this amount. While i deal and finish all the procedure the shop keeper suddenly change his word & telling me this offer is not for you but for those who will make bill on gst format, then again i agreed to follow this procedure, but shop keeper telling we don't know the offer product will come or not, it has very long procedure, then he is suggesting me to to take previous date bill & and not to go with gst format, i unable to understand actually what the case behind this all matter?
My complain & doubt here that the shop keeper will claim the offer by himself through my bill paper & not following the gst format,
I am requesting you to solve my complaint as early as possible