sub dequote {
   for (my $s = @_ ? $_[0] : $_) {
      s/^"//;
      s/"$//;
      return $_;
   }
}

{
   my $qstr = qr{"[^"]*"};
   my $num  = qr{\d+};

   my $response = '"F059"3,"Invalid Recipient postal code format for s
+pecified country."99,""';

   my ($error, $code) = $response =~ /^$qstr$num,($qstr)($num),$qstr$/
      or die("Unrecognized format\n");

   $error = dequote $error;

   print("error: $error\n");
   print("code:  $code\n");
}
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$qstr and dequote need to be adjusted to handle your (unmentioned) quoting mechanism.