Grid columns shrink in Kendo grid after excel export

I am new to Kendo-UI and Web-Engineering and I am facing a problem which I haven't solved after investing hours of time.

I have a grid with 8 columns, and a Excel toolbar button. When I fire the excelExport event, i show 2 more hidden columns to include their data in the report, and after that I hide them again.

My Problem is that my columns shrink for the hidden columns when they are shown, yet dont expand their width afterwards when they're hidden again.

Here's my script for the excelExport event:

<script type="text/javascript">
    var exportFlag = false;

    $(window).load(function() {
        $("#pr-grid").data("kendoGrid").bind("excelExport",function(e) {
            if (!exportFlag) {
                e.sender.showColumn("CallOff");
                e.sender.showColumn("LastChange");
                e.preventDefault();
                exportFlag = true;
                setTimeout(function() {
                    e.sender.saveAsExcel();
                });
            } else {
                e.sender.hideColumn("CallOff");
                e.sender.hideColumn("LastChange");
                exportFlag = false;
            }
        });
     });
</script>

I'd appreciate any help. Regards Paparis

$('#pr-grid table').width('100%');

<script type="text/javascript">
        var exportFlag = false;

        function excelExport(e) {
            if (!exportFlag) {
                e.sender.showColumn("CallOff");
                e.sender.showColumn("LastChange");
                e.preventDefault();
                exportFlag = true;
                setTimeout(function() {
                    e.sender.saveAsExcel();
                });
            } else {
                e.sender.hideColumn("CallOff");
                e.sender.hideColumn("LastChange");
                exportFlag = false;
                $('#grid table').width('100%');
            }
        }
    </script>