Paying rent and Housing benefits

A question about : Paying rent and Housing benefits

I am 21, working full time, studying part time and I live with my Mum, it is just me and her.
We live in a council house, she does not work because of long term sickness and she is on income support and other benefits. Before I started working she was entitled to 100% housing benefit and the rent was paid for by the government.
However when I started working the council informed me and my mum that I would have to start paying rent. They took my wage slips and based what I have to pay, on my monthly income before tax. At first it was Ј250. However they started increasing the amount, from Ј250 to Ј300 and now they are telling me they want Ј410. Telling my mum that if I did not pay this she would lose the house, saying she wouldn't want to lose the house she's lived in for 15 years.
My monthly income before tax is, Ј1600, but after tax it is Ј1250 and I have bills to pay as well as supporting my family financially. I am trying to save money to go to university in a few years, but I just cant when I have to pay so much. They are forcing me out of my childhood home and away from my mum, who needs me to help look after her.
I am uneducated about this system and would like a separate, unbiased opinion because I just do not feel like I am getting a fair deal. I am having to work overtime every week to try and get some money saved up.
I dont trust the people that my mum talks to from the council, she has spoken to someone separate from the council, briefly about another matter, and they were surprised at the amount I have to pay, and did not agree with the amount.
Just another opinion or someone that I could go and speak to would be just so helpful.
Thankyou for any reply.

Best answers:

• You can put your mum's details into www.turn2us.org.uk to find out what your benefit entitlements are.
  Because you are working there will be a non dependent deduction (which is based on your income before tax and insurance) from your mum's entitlement to HB and CTB.
  This is because it is assumed that you contribute to the household from your earnings.
  I do not know if the figures quoted are correct but you can check them yourself through the benefit calculator.