Factor fault

I brought a brand new Polo TSI comfort line on September 2016,unfortunately during the heavy storm the whole wiper bracket broke while I was driving. I then tried to inspect for myself as what could be the reason why it fell off only to find out that the wiper was hitting the bonnet when it was swaying and that s why it fell off. I have been to the dealership in Hatfield Braamfontein to notify them and to kindly request for an assessment but they are accusing me of moving the wiper from its original position. This is not acceptable as a paying customer, paying for a car with factory fault. Took the matter further to VW SA and instead of them making a thorough assessment they tell me that some one broke or removed the wiper and they are not going to replace it.