POOR QUALITY PRODUCTS

I bought 2 tyres for my daughters car. she is based in Cape Town. I bought the tyres at Vereeniging Tyres. brought the 2 tyres down to Cape Town and asked her to have it fitted. when I was back in Cape Town I drove her car and noticed that the tyres were noisy. asked her about it and she told me that it was noisy after fitting the 2 new tyres. she even took it back to the fitment centre to check that the tyres were fitted propery, wheels balanced and alignment checked. I bought 2 new tyres at Good Hope Tyres in Cape Town and the noise disappeared. I took the the tyres back to Vereeniging Tyres and they send it to their supplier. however, according to them, their supplier said that ther was nothing wrong with the tyres. my question to them is that why the noise after tyres were fitted and no noise after I purchased another 2 tyres and had them fitted.