Hello,
We are a team of professional Drupal developers based in Moscow, Russia. Over the last 5 years, we have implemented many various projects onshore and are now offering our services globally.
Architecturally I would accomplish this in a different way, i.e. reference your portfolio items using a field of type node reference rahter than using taxonomy terms.
However if you don't want to alter this the solution is to use contextual filter in Views and a custom function which will return portfolio nodes based on the current service nid.
I will provide more details if awarded.
Thanks,
Alexey