If you are sure that you will be receiving one ".xml" file for all the customers then
1. Read list of unique customers.

     
     @xmlFileNames=grep !/^\.\.?$/ && /\.xml$/,readdir(DIR);
The number of xml you get is the number of total customers.
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2. Loop through each customer and create zip.

   foreach my $customer (@xmlFileNames) {
         $customer =~ s/\.xml//g;
  system ("/usr/local/bin/unzip ${customer}.zip    ${customer}.xml  ${
+customer}.pdf ${customer}.xls");

   }
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