********* pricing strategy

I recently placed an online order with Pick n Pay. They have an option to amend the order until the day before it arrives. The next day, I amended the order as I wanted to purchase additional items. I noticed that the price of one item had increased. I called customer care and the consultant insisted that the price of the item wasnt for my region and even asked me to forward her a screenshot. I told her it's absurd as I have an order placed on that special price, she eventually conceded that the price had increased and is no longer valid in my region. I feel that this is highly ********* as my initial order was already confirmed and I cannot understand how adding items to my cart would alter the price.