No mobile phone service on phone purchased through Giffgaff

[#1]

I have just bought a refurbished Sony Xperia from Giffgaff with a new sim card. I wanted to keep my old number so I went through the 'sim swap' option by putting in the new sim code. I put this into my new phone. This was nearly a week ago now and I still am not ble to make calls or texts. I can use the internet, things have been transferred from my old phone, like app data for example but there is no mobile singal even after trying to add VPN settings but even that is unavailable.

I am getting some suggestions through from Giffgaff agents but they are all things I alrready googled and tried. 

Is there something obvious that maybe I am missing?

I have just factory reset the phone and set it up again and still nothing...

Help would be greatly appreciated as this is getting very frustrating!!

[#2]

@amie_wills86 

Hello you say you can use data but no signal ,

If there is no signal have you tryed sim in another phone to see if it’s a phone problem ,

also check for mast problems first put postcode here check for mast problems https://giffgaff.com/coverage-and-service#coverage
 
if if all ok try a manual roam to force network http://community.giffgaff.com/t5/Using-giffgaff/Force-the-change-of-SMS-settings/ta-p/4871794

if phone has no signal then don’t see how data can work 

you have checked phone settings network to see if network is on and not stuck on off that would account for no texts or calls 

[#3]

Hi :-)

Yeah I have put my sim in another phone and it works so it is not the sim, it is the phone. 

Data is working fine but it won't connect to any network and will not allow me to add VPN setting either.

I am going to have to take the phone to a phone shop I think to see if an expert might tell me whether it is just a faulty phone maybe.

I am really dissapointed as I have been a long term customer of Giffgaffs but there is nobody I can call to get immediate help when I just spent money on a new phone from Giffgaff which hasnt worked the whole time. 

[#4]

HOW DOES THE WARRANTY WORK FOR A REFURBISHED PHONE.

In the unfortunate event that your handset develops a fault you can ONLY return the handset to giffgaff using our returns process

LINK>> https://community.giffgaff.com/t5/Solve-your-questions/How-to-send-a-phone-for-repair/ta-p/10441573