hello G.,
I too had that problem. I was using the old ventaire bottle and then I switched to the new BPA free bottles when babies r us was giving the credit. Anyway, after the 1st week I noticed the measurement guide started to wear off. So I used a fine point permanent marker to right then on and I took them back to BRU. Well it happened again. This time I just sucked it up. But I was truly disappointed because the bottles cost so much more than the old ones. Fortunately, my daughter transitioned from a bottle to a cup about a month later (to my surprise). You should contact the company and tell them about your experience. Maybe they'll send you some more bottles are atleast a coupon. If not, take them back to the store where you bought them and complain.
My daughter is 17 mo and I've used Nestle Good Start since she weaned from the breast. We still use the phase 2 formula and we have never had a problem with it. I researched all of the formula's since my daughter had stomach issues when she was a newborn and I found that Good Start claimed they used the simplest protein compound (they break down the protein for easy digestion). If I were you I would definitely switch back to Good start since you didn't have any problems with it. Because the FDA strongly regulates baby food, formula, etc., I'm sure your son was getting all the nutrients he needs from Good Start. My philosophy is... if it's not broke, don't try to fix it.
Good luck,
Q.