Chinese phonemaker vivo is launching a new trade-in program in India. It lets you exchange your old phone for credit towards a new vivo phone directly from vivo's online store at shop.vivo.com/in. Cashify.in will be handling the exchange program for vivo and as a promotional offer, vivo will offer an additional INR 1000 to anyone turning in an old vivo device from today through January 19. To perform an exchange with vivo's new Xchange program, you first have to go to the vivo e-store and select the device you'd like to buy. Next, click on "check availability" to confirm...