Just a quicky, Nokia Lumia 520 does not need GiffGaff settings installing, Just turn pphone on off a couple of times and hey, everything working fine. Also no need for the 2020 text.
Hope this helps
Did the data connection work without you entering any settings then ?
What was the network the phone was supplied for ? (or was it purchased "SIM free" ?)
take a look here: bit.ly/jitbwindowsmobile
The phone is sim free, and no settings had to be manually put in the phone, when going to the APN setting it had giffgaff displayed. Also to check i did a factory reset then installed the sim, and again full service voice text and data.
Texting settings to 2020 worked for me even though I got a text reply saying that I would have to manually change the settings. Thanks