VAT charged on MRP is wrong.

Location/place: Guwahati(Assam)

Name of company/service: Pantaloons

We made some purchases from Pantaloons because they were having some sales. There was upto 50% off on most items.Upon receiving the bill it was quite clear that VAT was added to the MRP.The amount was 5% on clothes and 13.5% on shoes.I have found out that it is illegal to charge VAT on the MRP as MRP includes all the taxes and they can only deduct the discount and are overcharging in the bargain. I would like to complain against this brand so that they do not cheat their consumers.