Coolwinks — replacement of faulty lens of spectacles

I have online purchased spectacles of coolwinks. After 3 months on lenses white patches observed. After registration of complaint they told this problem is due to mishandling and not quality issue. Same is decided without inspection of material. And they denying the replacement. They don't have service station for inspection of problem and they are not sending the technician for checking. How can any manufacturer reject the complaints without any investigation.