I have just returned from travelling in the US. While there, I used a pre-paid tracfone sim card for my iPhone SE because the Vodafone International roaming networks did not have service in the area I was in. I am now on my way back to New Zealand, with a long layover in Australia. I had planned on using International Roaming while here, however, when I re-inserted my original vodafone sim card, the vodafone AU network shows up with full service, but I have no data connection. I'm sure there's a step that I missed, but nothing I have tried is working. Suggestions?