Adding,

use Data::Dumper;
print Dumper $config;
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to the end of your code reveals that the 'WR80B' key's value contains a hash ref whose only key is 'Runable'. You probably wanted,

print $config->{WhicsService}{Parameters}{Service}{Runable}{Value} . "
+\n";
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Actually, the 'WR80B' key doesn't exist at all until the print autovivifies it. Printing Dumper($config) before the other print statements shows the structure as XML::Simple constructs it.

Does your top level tag need to be <WHICS>? That will stand on the way of more sophisticated parsing, having the same tag with a different use for data.

The parent XML::Parser module gives a data structure which distinguishes between attributes and elements. It also places elements in an array, preserving their order. The simple version is probably good enough for what you're doing with configurations.