jbond23 Had the same problem today trying to help somebody else get started. Everything goes fine all the way to the bank’s visa security screen then giffgaff comes back with “oops something went wrong. It’s our problem not yours. etc etc”
Was the person trying to activate using their unactivated giffgaff SIM to connect to the internet? And which bank (just the name) was it that they were using?
Although this is usually possible, it depends on giffgaff having added the bank’s Visa verification website to the list of free to connect sites, and it’s possible that not all banks are on the list yet. The person in question should try again, using another internet connection, e.g. their home broadband, or public Wi-Fi in a library or cafe etc.