Poor service for sim swap

I needed to do a sim swap as per instructions from: https://now.vodacom.co.za/article/how-to-do-a-sim-swap-with-vodacom The consultant told me that the new sim is already active because I put it in the device. Where are the instructions warning that I shouldnt put the sim in the device? How can a new sim (bought for simswap) be already active by mere putting it in the device? If new sim is already activated, what is the new cellnumber for this sim?I have done simswap for data sim even if the new sim is already in the device.