The fastest way to accomplish this would be to add a column, such that it displays the total number of orders by a customer, then sort by this column
you want to use the countif function, which takes a range (the cells over which to look for the same customer), and the equality
So if A1 has the name of the customer, then put in the new column: =countif( $A1:$A4000, A1)
then you can copy and paste this formula down the rest of the new column and next to each order summary (I'm assuming each line is an order summary) you will see how many times that customer has ordered. Sort by this new column (in descending order), and the best customers will rise to the top, now it will show all orders, because you haven't done anything to remove multiples, that would require a macro, and it would not be automated, you would have to press a button
After of course the macro was coded and the button was linked to the macro, a lot of people do not like the security and trust center setting issues that come with macros, not a big risk if you know where your documents come from, but a small risk.