colinc1957 Hi there. It's not possible to swap your phone for a different model. But... You can return your phone back to giffgaff for a refund (within 21 days of delivery), giffgaff will instruct Ratesetter to cancel your phone loan (this can take 2 weeks to process), then you can buy your desired phone instead.
If you have changed your mind about a recent phone purchase, you’ve got 21 calendar days from when your phone arrives to change your mind and return your phone back to giffgaff for a full refund.
Please view giffgaff’s return my phone if I change my mind article to start a phone return, or, please take a look at this returning your phone guide to view the returns process in detail.