Still cant get this to work on my Xperia S. I tried a new APN which saved perfectly ok, and also edited an existing o2 apn. Neither has worked. I have full internet and phone services working normally though.
Ok i got it working now. So obvious in the end...Make sure the APN TYPE has MMS entered. Mine now reads 'default,supl,mms' and it works fine. I noticed none of the giffgaff settings have this included and i havent seen any mention of it on here so thought i'd pass it on.
mr cheerful thank you so much, I've spent days trying to get a giffgaff APN working on my Xperia Tipo and it just kept vanishing as soon as I saved it. I tried renaming the O2 APN to all the giffgaff settings and that caused it to disappear to! The only thing that worked for me was as you said - keeping the name of the APN as O2PayandGo, but then changing all the internal settings to giffgaff and away we go! ^^