Selecting a chart and changing it's style

So, I just created a pivot chart from certain information, but now I need to be able to change the chart style (I want to make it the xlBarStacked style)

This is my original code, and it works perfect,

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I run into problems when I try to change the chart style, because each time I run the macro, the number of the chart changes and I'm not sure how to set the chart to a certain name, or how to keep the variables floating for the following code, which changes the chart style and one of the colors of the bars:

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any suggestions?