Not transparent on pricing

Canal walk branch. I cannot fail the optometrist but their staff needs to be trained on current promotions and pricing. After choosing my frame, I was told the antiglare is 500 per lens and less the winter promo and discount,I asked to pay the balance of 697 in full.Upon collection, turns out it was an incorrect balance as Kurt did not apply the promotions correctly and I had to pay 400 extra as the antiglare was 700 per lens. I was absolutely gutted as one does not always have extra laying around which is why I asked for a breakdown of pricing. The fact that the staff did not get it right should not have been to my detriment.