Amazon India — after sending wrong product they are not in mood pick it back

Address:

Bardhaman, West Bengal

After sending wrong product they didn't take replacement request for the same and i have to place a refund request. after one week they didn't pick the product and again they assured me to wait for 2 day and they re schedule the pick up and again after 4 days they again gave assurance that this time they will pick the product and it has been half month but they didn't do anything... will anybody sugget me what to do.. plssssssssss