Turtle Limited — misleading advertisement

The Turtle Showroom at Guwahati are advertising 50% discount in the month of July 2018. I went to a Turtle Showroom to purchase shirts & selected two shirts having MRP Rs.1599/- each(Including GST). As per the advertisement @50% discount I should be charged Rs.1599/- for two shirts. However at the time of billing he charged me Rs.79.95/- extra i.e Rs. 1678.95/-. On enquiry the store manager informed me that GST @ 5% is being charged on the discounted price. Since the initial marked price was including GST, the discounted price is also including GST & charging of additional GST is plainly misleading advertisement as now the discount is only 47.5% instead of 50%. I being not agreeable to this sort of cheating cancelled my purchase. I also request everybody to resist this type of misleading advertisements.