Pivot table and sorting data

I have attached spreadsheet of sample data. Basically I need to group the data by customer/supplier, so I have a total for each customer/supplier and then a way of maximising the total so I can see the transactions that this consists of.

My problem is that I need a way of sorting the data firstly by customer/supplier name, and then from largest to smallest total sales/purchases.

I have come to the conclusion that a pivot table is the best option here but I can only seem to sort data by one column.

Any help would be greatly appreciated.