Medlife — Not issuing refund even after 6 days

I have ordered a medicine from medlife with order id OR7448KEC-011A with payment by amazon pay of ₹578 but when a delivery boy came he told the product is cash on delivery and i was shocked when i saw in the product that it was written cod of ₹700, that was different amount and by the way i have done payment by amazon pay, and i called medlife and they have not taken any action regarding this only they always tell to wait for 72 hours i have waited for nearly 7 days but i did not receive any product after even 7 days i again called medlife they told to wait for another 2days, they are always wasting customer time after 7 days delivery boy called me they are returning the product because it was cod and they are demanding payment but i declined the product because i have paid by amazon pay so why i should pay again so they returned the product but medlife is not issuing my refund. please check the issue so that medlife should refund my payment, please help me in providing my refund