It sounds like you just have a simple sales issue, and thankfully a high quality product :)
The solution is simple, and you seem to have realized it already: you need to reduce the friction in your location for getting customers into your "front door" and providing them with (what I'm assuming) is a proposal.
Also, feel free to use the word "agency" to describe your combined services. It's what we do :)
So, my suggestion is to try reaching out to sales professionals in your area (Paris), and more importantly, with experience in your industry. You'll need to figure out how commission or payment will work, and then let them work their networked magic.
Achieving sales leads is really just about your network. So if a sales person simply isn't within your budgetary reach, the next best thing you can do is just have every employee of your agency be their own salesperson. This means reaching out to colleagues from completely different industries, friends, successful people in business that you may have known from grade school, etc....
While sales seems like a crappy process at the start (yes, you are just asking for work from people), what you're building is long term, quality relationships with these people, especially if your final deliverables really wow the end client. From there, you'll find that your happiest clients will do most of the traditional 'sales' work for you :)
Hope this helps! Feel free to give me a ring any time.