lense replacement

I was very happy to know that Newcastle finally had a Torga Optical. Despite a stern warning against the group I went ahead regardless and booked an appointment. I was pleased with the service until now. I noticed "scratches" on my right lense. They got worse and worse. A friend whom is also in the optical business advised me that these were not scratches but the anti reflex coating that's busy cracking to the point where I cannot see out that side properly. I went to the franchise in Newcastle and the assistant said it was scratched and also after the guarantee period has lapsed. This is utter nonsense as I know an optical checkup to be done every two years. I have been wearing glasses since I was 9 and am now 39. She further went on to say I am responsible for the cost of a new lens at nearly R500 they will offer me a discount of 40%. I do not see why I should replace at my cost. I have a good mind of getting a quote from an optometrist in town and passing it on to torga for payment because these glasses are poorly made and damaging my sight even more.