Contract subscriber struggling with SIM swap

I upgraded my contract recently and am now struggling to do a SIM swap. I followed the steps as given on the MTN website for contract subscribers (https://www.mtn.co.za/Pages/SIMSwap.aspx) and received an sms to say I can start using my new SIM once my old SIM stops working. 24 hours later my old SIM is still working. I phoned the customer care line and was then told I need to go into a store to get it sorted. I upgraded over the phone to save time and was told I can do the SIM swap without going into the store aswell. What should I do now? I cannot use my new handset. What is the point of upgrading over the phone but having to go to the store anyway to do the SIM swap. Please assist, I would love to be able to use my new handset, which I am now paying for, asap.