iPads in Australia did not have the ability to connect to Australian 4G due to a frequency mismatch. It is a hardware problem with iPads and the ACCC took Apple to court successfully for false advertising. It was corrected in the 4th gen iPad recently released. If you were sold the iPad expecting to connect to 4g and it won't, you should have recourse.
https://www.google.com.au/search?q=i...&client=safari
John