Safari cannot open page because your iPhone is not connected to the internet

I have a 3 month old iPhone 6S running 9.2.1 OS. After my phone provider Vodafone sent a text saying "It looks like you've swapped your Sim or updated your software. If you want to continue using data, you'll need to update your settings. We'll send you these by text shortly." I had no problem and had not switched my SIM, and was all okay nothing wrong, but I did follow the text to the weblink to download the updated phone settings thinking Vodafone needed me to. Later I discovered, when I left my house so NOT on wi-fi, I could NOT get online via Safari. Safari shows a blank page saying above (my subject line). After several calls to Vodafone, 2 techs telling me to change my APN settings, force phone to reboot (hold home button and off button together) still no results. Further call to Vodafone, was advised to go into their store and test my SIM card in another phone. I went in, the advisor didn't do this, just swapped my older SIM with a new one, said restart and wait half an hour, should all be okay. Still had same message. Returned to store, got the manager to put the new SIM into another phone, that phone DID get the internet. So now my phone seems the suspect. However, following day, my engineering husband, not an Apple user asked me to try a different browser on my phone. I downloaded Firefox and yes, I can get cellular data and websites using this browser. My question is, What happened to my Safari? Can I reload it, or how do I fix the Safari browser to make it work again. I can use Firefox but Safari is a native app, how should I restore it to working order or must I take it to Apple to fix? I followed one advise on this support website to turn off Safari and reboot phone holding down home and off button simultaneously, but it did not fix Safari. Should I sync my phone with iTunes, can iTunes remove the app and replace it? Any advise welcome please.