Hi @ujo55 The answer to your question is actually very simple, anyone having an active giffgaff sim card can simply load up their contacts list with as many random numbers as the list will hold and give them fictitious names, then open the giffgaff app and click on "contacts" they will be presented with a list of all the numbers in their contacts list that are on giffgaff. All they need to do is make a record of them, empty the contact list and start the process all over again.
My long experience of the giffgaff app on android is that it is particually inept at identifying giffgaff numbers. Currently it shows 2 out of a known 15 gg contacts. I am sure the new app will improve things for those of us who have a legitimate reason for needing to identify members.
giffgaff sims with free calls to giffgaff numbers, without a goodybag or airtime credit, can quickly establish other giffgaff numbers by getting free calls
@gcase64 giffgaff numbers by themselves are not really the issue. It seems fraudsters and hackers obtained email addresses, passwords, mobile numbers from other less secure sites and then they try and exploit the information by taking over giffgaff accounts. Mobile numbers of themselves are not the problem.