So you have no signal at all?
Are 02 working on the mast near you?
Have you also tried all the usual troubleshooting ideas below?
*Check your phone settings are correct to receive gg signal
See this link to guide https://community.giffgaff.com/t5/Settings-for-your-device/Internet-and-MMS-settings-APN-guide/ta-p/3489121
which covers all makes of smart phones
*If settings are ok but still no service, Check your network coverage status via link https://giffgaff.com/coverage-and-service
to see whether there are outages or faults with the network signal (EDGE, 2G, 3G, and 4G) in your area.
Simply enter your postcode link www.bit.ly/ggservicestatus
for local status
NOTE! The information is updated hourly, so it’s worth checking a few times as your particular issue may not show up first time.
*If the signal is good try doing a manual roam… see link below for full guide which allows you to select the network provider manually
GUIDE TO MANUAL ROAM https://community.giffgaff.com/t5/Tips-Guides/Manual-Roam/td-p/3345471
*Also turn your phone on to Airplane mode and ON and OFF every 30mins to update the gg signal
*Finally please try swapping SIMs with another phone to see if there's a problem with your phone or the giffgaff SIM.
*If still no joy contact an agent for assistance
All services (calls, texts & data) not workinghttps://support2.giffgaff.com/app/ask/Calls-texts-and-data/My-services-arent-working/form/Please
Allow up to 24 hrs for a response. Agents work 7 days a week from 8am to 11pm.
Check for replies here:https://giffgaff.com/support/questions