Faulty car from Mazda South Africa

Purchased a brand new mazda 2 in oct 2017 from B.B Mazda tzaneen the aircon stopped functioning from June 2018 and got it checked on 10/ 08/ 2018 ( last week Friday ) and I was informed that the very same car with warranty I had to pay for diagnostic test which costed R669 and was told to fix the air con as it should be replaced and was probably hit by a stone according to their diagnosis and it will cost me 9,6 k to replace the part I then contacted Mazda head office as to what they meant by warranty they claim they only cover faulty parts and this is regarded as an accident and I was even told that I am the only unhappy customer