I've got to assume that giffgaff being cheaper is for a very small selection of users, even visitors. If someone's just using calls/texts, then other providers were always cheaper, if it's for data, then while it may have been, it's not been for a year since I left them for 3 like most other people that use a lot of data did. If you don't use a lot of data, then you can probably find someone that provides the data you need cheaper and better than giffgaff do.