Vodacome are the last ****s in the world

I took a home internet contract that comes with a router, it was never disclosed to me that the router was preowned. Now the router is not working anymore and i am told that it has reached the end of life. The 24 month warranty was also changed to 12 months without my knowledge. Now vodacom refused to give me a replacement router. How do i pay 36 months for a router that no longer works