Poor quality , high cost

After a very long time with them, they glass quality is going bad, I did my glasses at wonderpark torga opticle. They dont last. They went for a change within a year because of unknown defective stuff. Now 6 month down the line the same lines appear. All they can say is I dropped them. How do I drop something I paid so much for .

January 2018 new glasses Dec 2018 defective stuff (replaced ) May same things appear... their answer "you droped them"

I'm changing this company I loved for a long time . Their supplier might be using cheap materials to produce glasses. *loyal customer gone*