Faulty Modem Routers

I took a home date contract from Vodacom in January/February. I have been to the store more than three times already with a faulty router. Their router only works for a month and a half and then gets faulty. Each time I have to wait more than three weeks for the repairs. Recently I had a problem with the router again, waited three weeks and they gave me a faulty router again. I went back and was told they are taking it for repairs so I have to wait another three weeks. I am really fed up already with paying for nothing. I am considering closing this account and they can keep their router. I've had this contract less than six months and I'm tired of running back to the store with a faulty router.