Markings on Nature bottles

We bought bottles for our baby when I was 7 months pregnant. My baby is now 4 months old and has been on the bottle for 2 months. I'm very disappointed to say that my baby is not even using these bottles for 6 months and the markings are fading already. The quality of these bottles are pathetic. I cannot explain how upset and disappointed I am in Avent and the quality of these bottles!