Hi,
This is very similar to the Slow Moving Items scenario outlined here: https://help.sap.com/saphelp_nw73/helpdata/en/4a/124866ca771b41e10000000a42189c/frameset.htm
The only major difference is that the link talks about slow moving "items" i.e. products while you need slow moving "customers". Replace 0MATERIAL with your customer characteristic in the link and that should be your solution as well.
Regards,
Suhas