We all depend on agencies, and we all have some common problems that come up in our work with them.
Sales Agencies
Agencies are really sales agencies. They earn their living by matching you with a client who needs your skills set. The majority are honest businesspeople who don't want to do much more than that, and to take their commission.
But competition is fierce, so agencies sometimes veer off the track, sometimes without even realising it.
The CV Goes AWOL
Ever had an agent send your CV off to potential clients without consulting you? Then another agent that you actually work with calls to say that the client already has your CV. Or sometimes you find that your CV looks a little different--your agent has 'tweaked' it creatively on your behalf.
All this is illegal: you can complain to the Recruitment and Employment Federation.
The Job That Isn't
Another good one is to find that an agent has put an advertisement on the job board for a phoney job. The agent uses the ad to collect CVs for the database, or to see what's out there in case something comes up. This one is also illegal, so complain to the REC for this too. As is that phone call from the agent who loves you and has just the perfect thing for you...only it doesn't exist--the agent is just checking out market conditions.
Have Your Say...
When I first started contracting 8 years ago I fell for every trick in the book. 
Mike James
Send us your comments Deeply (Phoney) Concern
Indeed, one of the worst traits that one encounters amongst agents is the desperately (phoney) concern for your welfare. All that deep concern about how you will like this new job...and then if it doesn't work out, you never get a call back. Or they pretend that they have your best interests at heart when, as we all know, agents work for the client. They obviously are more concerned about the fee-provider than about you. But some will pretend the contrary. Unfortunately this is simply the nature of middleman businesses like this - estate agents being the other common one. You just have to put up with it, and take what you are told with a pinch of salt.
Contact the REC if you feel you have been treated unfairly by an agent
REC
The Callback
One does never hear back from agents if they can't place you. It's annoying; you don't know whether or not to keep looking for more work. On this one, we can't blame agents all that much, because they get so many applications for single posts, that it's really too much for them to let everyone know. Just ask the agent while the interest is still there how long it will be before you can expect an answer. It's not perfect, but it has to suffice.
Margin Grabbing
Agents live from the margin they take on your total fee from the client. Nothing illegal here, and there is no strict rule on what is fair; you, the contractor, have to negotiate a good deal. But aren't you tired of arguing for hours with agents to get a decent margin?
On the subject of margins, some agents do go a bit over the top when renewal time comes around. They tell you that you can't go back to the client unless they say so (it's in your contract as a restrictive covenant) and so you have to take a cut in fee. We are advised that this strategy won't stand up in court, so just say no and go straight to the client.
Challenge an agent who tries to cut your fee based on a restrictive covenant
REC
With all this said, the best strategy for dealing with agents is to understand where they are coming from. They want to sign up your deal as quickly as possible, and to go on to the next one--that's not their fault, that's how the business is structured today. Don't expect more from them than they can give, but don't let them abuse you either.