Trade-In - serial number not recognised on iPhone 6 plus
I'm trying to trade in my iPhone 6 Plus, but the serial number keeps saying :
The serial number entered doesn't match the device selected.
Yet its true, iPhone 6 Plus and 128GB capacity.
Yet if I check it on the check coverage page its fine, it comes up.
https://checkcoverage.apple.com/gb/en/?sn=
So how come it doesn't come up when I'm trying to trade it in, when buying a new iPhone 11?