Sorry to hear that
So the tracking number is not listed next to the payment confirmation info?
1.It may now arrive on Monday now as it's the weekend.
2.I'd contact the carrier and get an estimate time of delivery
3.SEE GUIDE See to phone deliveries
Between 19:01 Sunday and 22:00 Monday - Tuesday
Between 22:01 Monday and 22:00 Tuesday - Wednesday
Between 22:01 Tuesday and 22:00 Wednesday - Thursday
Between 22:01 Wednesday and 22:00 Thursday - Friday
Between 22:01 Thursday and 19:00 Sunday – Mondayhttps://community.giffgaff.com/t5/Using-giffgaff/Guide-to-Phone-Deliveries/ta-p/15633925
If you’re not available to accept delivery the person receiving/signing for it must be over 18
4.I'd also contact an agent now to let them know you have no tracking number because the email did not come throughhttps://support2.giffgaff.com/app/ask/Phones/Buying-a-phone/form/
Buying a phone
hope this helps