24 month guarantee not bieng honoured

We bought a Ryobi 36cc chain saw at Game in October 2015, the ad even in this weeks paper says: 24 Month guarantee which Game advertises. We used this chain saw once in November and once in December, in January it stopped working, when I took it to Game in South gate, they sent it to Ryobi for repairs, Ryobi wants us to pay R600 rand for repairs, yet it is under guarantee, how do you ask someone to pay for repairs for an item that is guaranteed, I want a full refund on this product, because not only have you sold me junk, but now you go back on your adverti*****t which guarantees customers.