Employer abuse, where to complain?!?

I am writing this post because I need some advice on how I can sort out the issue I will relate below. Any advice would be much appreciated. I would mainly like to bring these facts to the authorities' attention.

I am sure that the UKBA is trying to do it's best to tackle border tax fraud, smuggling and immigration crime and I was sure that they will follow up my complaint with appropriate action as the concerns that I will mention are of a very serious nature and detrimental not only to the HM Revenue but also to the people that are being mistreated and abused. Unfortunately it's been most than 6 months now since I've first contacted them and no signs of reply yet.

I have been hired by Ms Andrea Mattia to work in one of the Kiosks belonging to Andrea Mattia Concessions (she operates in Outlet Shopping Villages and has more than 60 only east Europeans nationals employed) as an Assistant Manager and I had the unfortunate chance to see the manner in which she runs her business and the treatment of her staff. You should know Ms Mattia employs only foreign nationals from Romania and Bulgaria and she uses the grey areas of the somewhat awkward working regulation set out by the Home Office for Romanian and Bulgarian nationals in order to bully, abuse and mistreat her employees almost to the level of modern slavery.

The Home Office states that nationals from either country may work in the UK as long as they are either self employed or in possession of a work permit. Ms Mattia however has taken great care not to mention this information to her staff, which she brings from the respective countries herself. She also assures them that they will be paid excellent rates and be given free accommodation and that they will also be entitle to a free meal everyday all as part of a great opportunity to work and live in the UK, unfortunately the reality could not be further from the truth.

In fact Ms Mattia does offer accommodation for her staff but not for free as promised, her generosity means that 10 or more adults will be living in one house, which adds up to around 4 adults per room. She also makes sure to force her staff to hide while the council comes round to check. She also keeps one month’s deposit from each employee with no proof or receipt, and if the employee decides to leave she will ensure that none of the money is given back by using preposterous and outrages excuses to deduct from the employee’s deposits. However, if you thought that this woman has any decency left that you are wrong, because she also makes her staff work in excess of 60 hour weeks for months on end. No days off, no holidays! Because as she personally mentions to her staff on a regular basis “I am British, what are you going to do about it!” At the same time she also makes sure to hold back money from their wages for taxes, quite admirable if only her staff were registered to pay taxes, but they are not as they are Self Employed and she has no right to hold back their taxes or they have no right to work at all because she has never lawfully employed them. She also makes sure to remind her staff that they are worthless illegal immigrants and that without her help they would be sent back to where they came from. Ms Mattia’s outrageous treatment of her staff is not only for business because she also gets them to clean her private residence on a regular basis, with no pay obviously, because they are nothing more than modern slaves!

I very much hoped that the central and local authorities will take the right steps in order to put a stop at this atrocious behavior which is a disgrace for the British system, but unfortunately as far as I am aware none of them has approached this company yet. I understand that I am not the first person to complain to the UKBA Agency about this particular case and I wonder how come she is still there, running her business, abusing people and treat them as slaves, making loads of money without paying taxes and no one has done a thing. I've been there, I know her paper work, everything she does is anything but legal and still...she is there. I wonder how this is possible.

Recently, I've been threatened by Andrea Mattia's friends, that if I will go ahead with contacting the Home Office and HM Revenue I will be harmed, the police is following up this case as well. Why is the Home Office not doing anything? Is it because she is a British person, was she right, there's nothing we can do? I would like to get a reply from you and please feel free to contact me if you need any further information.

I would also like to contact national media, hoping someone will give a helping hand to these poor people who are being maltreated and abused.

Thank you very much for your time and support.
Additional Details
I don't really know how to reply and I am doing it here.

I am romanian and I have the right to work in the UK.