I've worked in the financial and lending sectors and have dealt with many people in debt who have been victim of debt collectors, debt management companies, shady lenders - you name it, I've seen it happen in this business. Straight away there are elements of what you describe which strike me as, at best, immoral, at worst, illegal. If they are wilfully misleading people into thinking this is the right way to deal with a debt they are committing fraud (obtaining money by deception). This practice is often used on 'old' debts - ones which lenders have been chasing for a long time with no success so they give up on them and take the small amounts such companies pay to buy the debt. As the customer, there are many options which can be used to deal with this, most do not involve paying out money. And certainly not the hidden fees you mention.
Keep records of what is going on, and gather evidence if possible. The 3 main bodies they will be answerable to are OFCOM (telecommunications), the Office of Fair Trading and The Financial Ombudsman. In fact look at this from the OFT - http://www.oft.gov.uk/news-and-updates/press/2010/105-10
They probably have in place certain procedures which they will enact should anyone report them or complain. It's only when someone on the inside (like yourself) exposes these things that it gets dealt with. All the time they are able to cover their tracks they will get away with it. There was a very interesting episode of Panorama on BBC1 last week about call centres - they were all breaking the law but had scripts prepared to read out when questioned on their activities. Until they showed them undercover filming they had done!
As for your position? I totally understand how you must feel, jobs are thin on the ground right now and no sane person chooses benefits. You're trapped! Well start looking around right now, send out your CV and covering letters even to companies who aren't advertising. Speak to your local Job Centre regarding your benefits entitlement - you may just lose out for a few weeks, it depends on how they judge your reasons for leaving. Maybe you should contact the BBC, ask them if they want to do a follow up on the Panorama report? Tell them you know someone who's willing to become an undercover reporter...
Keep your chin up, only act on this if you're able to - as much as companies like this need to be exposed it's not worth causing yourself more stress. And it's certainly not worth continuing in an environment which makes you feel so low.