Best answer by Mohammed
Welcome to the iD Community.
When you upgrade, be it to a SIM-only or a handset contract, we'd send out a new SIM.
This is usually inactive and you'll need to get this activated and swapped over.
When you check the iD app/account, what is showing for your current tariff?
How did you process this upgrade to a SIM-only?
EDIT: I've moved your topic and renamed this for clarity. It can now be found in the Plan types, upgrades & plan changes section of our community.