Upgrade confusion and wrong messages

I have had a disappointing experience at the Vodashop Cresta: I enquired of Vodacom if one of my contracts are eligible for an upgrade. Vodacom responded with a message that I can upgrade immediately. When I arrived at Vodashop Cresta, I was told that I have to wait until the end of January or the beginning of February. I am upset that Vodacom says one thing and the shop says something different. I have been a loyal Vodacom customer for about three decades and do not appreciate these confusing messages.