Your on the right track. Use only two series… one for the bars and one for the line. to inject additional space between two bars leave a zero value in between the actual values. Example:
WA is Bar series
WC is line
Days at top are category labels (X-axis)
The bar space is made by inserting 0 values in “Data” not adding series. X axis labels are not seen if left blank such as missing Tuesday, Thursday, etc…
If needed you can use additional bar series just keep the data in the same pattern as you use for your other bar data - blank columns should be aligned where you have used zeros for spaces.