Customise data table in Excel chart?

A work colleague is preparing a report that has several charts that include a data table. The labels in each column of the data table (which replace the X-axis labels) are broken up over several lines because the width of the column is less than the width of the text label.

We can’t just drag the chart out til the column widths are long enough as this makes the charts stupidly long. What we would like to do is turn the labels so they run at 90-degree angle (ie up and down rather than left to right). We know this can be done as we have a report from another organisation which has done this - whether they used Excel is another matter.

So, is there a way to customise a data table in a chart in this manner, or is there a work-around, or is there an add-in or macro available to help us out?

Thanks