NYCDOMINIC, regarding how to find agent information, here are a few links you might find useful.
The
first is a post on the
Writer Beware blog that is a good place to start. Like the Bewares & Background Checks here, Writer Beware is a mine of information about what's good and bad out there for us writers, and how to tell the good and bad apart.
Next you can browse the Ask an Agent forum here, which is a great place if you have specific questions about what to do with a query and what you do if an agent expresses interest, and so forth.
As for specific agent information, you can go to
AgentQuery.com and
QueryTracker.net. Before you do that, though, you might make a list of screenplays you admire and that you think are similar to the kind you write. Find out the writers' names and you can search online to see who reps those writers. That way you have a list of agents who might be interested in your style and genre of writing. This is the sort of tailored approach that works best, and which the query services don't provide. It takes time and effort, but of course your writing is worth it.
I hope the query service works out for you, but I must agree with everyone else here and say that I've not heard anything good about that kind of service. Agents tend to find them annoying and unhelpful, and you really don't want to annoy an agent before he/she even looks at your query, right? Anyway, best of luck!