Frastrated with Standard Bank mobile

I use a standard Bank mobile sim card, which I had canceled the contract to prepaid on the 1st of July 2023. I lost my phone that had a standard Bank Sim card on the 4th and when I called them they said I should go to a standard bank branch to get a Sim card and call them to do a Sim swap, which I did on the 5th of July. The Sim was inserted in my current phone and does not seem to connect to the network. I have called several times and keep on being told to restart phone and change my phone settings with no help. I use the phone for work and now I can't even setup the apps on this new phone since they send OTPs to the number that is not connected to the network. When they called they said their Sim card is fine but no solution was provided