Charged for two routers i do not have

Last year in 2014 I received two routers from Vodacom on a contract. Upon receiving them I realised that they are not connecting/working. I told Vodacom to collect them and cancel the contract and in December 2014 a courier company was sent to collect them. They were collected but to date I am still paying for them and I do not have them. I need to pay because they are still billing me and if I do not pay I was told that it's going to affect my credit record.<br> <br> Please assist.