Changing Data Values
To change a data value displayed in the chart, all you need to do is set its X and Y properties. For example, the following statements change the fourth data point in the second series to (10.5, 7.7):
With Chart2D1.ChartGroups(1).Data
.X(2, 4) = 10.5
.Y(2, 4) = 7.7
End With