Vodacom CatS30

In connection with a Cat S30. In November 2016 I bought this cellphone on contract upgrading my old cell. The Vodacom store is situated in Hartswater NC. After a few months the loudspeaker was not working. They took it in for repairing and I received it 6 weeks later. In the beginning of 2018 this cat cell fell into water. Not working at all. Back to. the vodacom store in Hartswater to repair it. After a month they phone me to inform me I must pay four and half thousand rand to repair the cell. That was supposed to be water resistant with a monthly instalment of R349pm. Vodacom still has the cell beause I refuse to pay that money for a cell that is still under a gauranter of 2years that will be Nov 2018. I still pay my instalment every month without having a working cell. Can you please advice me how to proceed in connection with this cell advertising as a waterproof cell??! Thank you in advance, Mrs J.C.Snyman 6/5/2018.