Go to settings
Look at the number on ICCID
And Jot that down carefully on some paper,
Then double check it
there should be 19 digits starting 894411
Log in hereHttp://giffgaff.com/activate
Put that 19 digit number in the box provided
And click the yellow activate your sim button
Does it say the sim is already active
Does it say
"sim swap isn't possible between 9.30pm and 4.30am" ?
If it says the latter, you need to complete a sim swap with the 19 digit sim serial number tommorrow
Once you repeat the initial steps tommorrow,
You'll arrive at a sim replacement page
Click the yellow button
"Yes I want to swap my sim"
On the next page click the yellow button
"yes I'm sure"
Your sim will usually start within 30 minutes
(switch your phone off and on every 10 minutes or so)