Returning the device

I did online application for iphone8 contract on the day they delivered the device i notice that its a preowned phone same day i called the customer service requesting that I'm returning the device cant pay 36 months for a second hand. Almost two months now since 29 June 2022 calling no one is willing to help me the only communication from Vodacom is the invoice of 471 for a device i never used it still in the box and the sim card is not active .Disappointed with your service