SonyXperia-Faulty-Not water damage!

In Dec (17/12/15), I upgraded my contract at Vodashop in Blue Route Mall, where sales agent highly recommend the Sony Xperia, as it was far superior phone. He described great features and the fact that it was waterproof! A few weeks later (04/01) the top half of my screen stopped working and then it didn't turn on. I was away, little I could do, but use my old phone. I manage to go to small mobile shop, who reset the device & it turned on. Unfortunately, not all fixed, as some icons work and others didn't. Software? (05/01) Formally logged issue (13/01/2015), few days later, received a call - phone was ready for collection. (16/01) After a shop visit (unable to find phone), agent called & phone ready to collect. But, i confirm no charge? Agent then said water damage, phone broken! Collect broken phone? This brand new 'fab' phone have water damage! It was inconceivable to me. (17/01). Returned to shop, agent assured me, management would contact within days. (19/01) No word. Research & chatting to another Vodacom & Sony Xperia user same issue?? I am completely unsatisfied and disappointed with Vodacom's service AND Sony's product. This is absolutely unacceptable! PLSE HELP!