Hi, did you use a debit card or a top up voucher?
When you clicked to pay, did the page say it was successful?
Did it say "its not you it's us" or done other message?
Can you see your number next to your username here
Can you also see your balance and goodybag or does it say
"we're activating your sim" ?
Have you received an email from giffgaff confirming the activation with details of your new giffgaff number?
Which phone do you have?
Do you see signal bars and a connection symbol
(3G, 4G, H, E, gprs)
From your phone keypad dial
Star 100 star 7 hash
And press call
Do the same with *100#
What word or words do you see on the phone screen?