The mdr is shown in Paytm machine upfront I bought a bike from Honda and paid small amount then they checked the machine, was charged 1.18% then I paid the remaining amount with mdr charges. As I was getting 2% anyways on Timesblack card and was achieving the milestone as well so...I dont think processing fee is displayed on POS machine.
Do a small transaction like rs 50 or 100. Check if it shows processing charge or mdr on POS machine. I doubt it will. Then ask dealer to check his settlement sheet sent by bank either on t+1 or t+2. That will clearly show mdr. Verify there.
I doubt 3% is charged as mdr for any Indian credit card. For amex may be.