Flying Machine — charged gst 2 times

Address:

Dehradun, Uttarakhand, 248001

I have purchased 4 garments from flying machine showroom from pacific mall dehradun.
They have given me 40% discount and charged gst again on it. How is it possible no other brand does that !
4 garmets mrp total is Rs 8296/-
After 40% flat discount it should be Rs 4978/-
But i am charged 5737.
Bill is attached please find the attachment below.