function FillInFields() {
    if (document.getElementById('sameAsBilling').checked) {
        var bName = document.getElementById('bcompname').value;
        var bAddr1 = document.getElementById('baddr1').value;
        var bAddr2 = document.getElementById('baddr2').value;
        var bAddr3 = document.getElementById('baddr3').value;
        var bTown = document.getElementById('btown').value;
        var bCounty = document.getElementById('bcounty').value;
        var bCountry = document.getElementById('bcountry').value;
        var bPostcode = document.getElementById('bpostcode').value;

        document.getElementById('dcompname').value = bName;
        document.getElementById('daddr1').value = bAddr1;
        document.getElementById('daddr2').value = bAddr2;
        document.getElementById('daddr3').value = bAddr3;
        document.getElementById('dtown').value = bTown;
        document.getElementById('dcounty').value = bCounty;
        document.getElementById('dcountry').value = bCountry;
        document.getElementById('dpostcode').value = bPostcode;
    }
}