Myntra.com — I got less amount of money at the time of cash on delivery.

I ordered a T-Shirt and it got delivered today at 1:30 pm. I had to pay Rs 349 at the time of delivery. I gave him Rs 500 and he returned only Rs 50 instead of Rs 150. I thought he will give me Rs 100 more but he wore his helmet and went back. This is my Order ID # 1198519 [protected] and I want my Rs 100 back. I waited for mote than half an hour thinking that he might be back but he didn't come.