wrong product delivery

hello
i have ordered a lenevo cell phone from amazon,in and recieved it on cash on delivery with an amount of Rs.14000/-. But they delivered another product. Moreover, their online status shows it undelivered.. when i talked to their customer care representatives , they are regretting for that product delivered to me. Now i want my money back on the return of that abovesaid product …
Invoice number:MAA4-221271
invoice details:TN-MAA4-151792751-1718
invoice date:25-08-2017