try to restart your phone
If you want you can have the number transferred over the next day however, The PAC code MUST be submitted to giffgaff before 15:00 (3 p.m.) on the day of your request.
Time / Day of request Earliest transfer day
Between 15:01 on Friday and 15:00 on Monday - Tuesday
Between 15:01 on Monday and 15:00 on Tuesday - Wednesday
Between 15:01 on Tuesday and 15:00 on Wednesday - Thursday
Between 15:01 on Wednesday and 15:00 on Thursday - Friday
Between 15:01 on Thursday and 15:00 on Friday – Monday
NOTE: Requests made on Friday are processed on Monday. Requests made on Saturday and Sunday are processed on Tuesday. Also no transfers occur over public holidays e.g Bank Holiday.
As with SIM activation's number transfer process can take up to 24 hours to complete but usually 90% of transfers are completed before 3pm on the chosen transfer day.
This is what happens on the day you transfer - you'll experience a loss of service at some stage between the hours of approximately 9am and 6pm - typically this is no more than a few hours but can take up to a day, so please make plans so you're not caught short.
For a detailed guide on the number transfer process check out this http://community.giffgaff.com/t5/Getting-started/How-do-I-keep-my-current-mobile-number/ta-p/3521127knowledge
If your number transfer isn't completed on the requested day ask a agent to investigate. To contact an agent go to your My giffgaff page and scroll half way down on the left hand side you will find the "Ask an Agent" hyperlink. This is also the location to view the reply's sent by agents to any questions asked here is the link to contact an agent https://support2.giffgaff.com/app/ask/Number-transfers/Transferring-my-number-to-giffgaff/form/
A response from an agent may take up to 24 hours during busy periods, but they usually reply in a couple of hours. Agent replies can be found here https://giffgaff.com/support/questions