The name label/title isn't all that important however it could mean you was only sent the calls and internet settings not including mms when you first inserted your sim as it's normally done automatically, when you click the giffgaff.com settings to view the greyed out data some important ones regarding mms are:-
MMSC
MMS PROXY
MMS PORT
APN Type (default,supl,mss)
If any of those are blank or different from giffgaffs recommend setting it won't send.
I'm kind of at a loss as to what your next steps are especially if you cannot get a manual entry to save.
I would recommend adding the settings again and deleting the existing one, turning the phone off for 60 seconds and turning it back on.
>> However I don't want to make matters worse for you in the event it doesn't work.
----
Finally this has never worked for me when trying it in the past or even just now as I tried it for yourself.... but if you send a new message saying :-
settings
(To #) 2020
It may reply with the giffgaff settings attached you simply click it, save it and reboot your device.
Whenever I try it though it simply says we're busy try again later.
Its worth a try though I suppose.
As a last resort you could always reach out to the community over at giffgaff.
https://community.giffgaff.com/t/help-and-supportSorry I cannot help more, I hope you get it sorted.
All the best!