I could lose my home because of CSA mistake

In September 09 i recieved a letter from the CSA stating my payments were going down to £7 a week due to a change in the PWC circumstances. I knew this to be wrong and questioned it three times. the CSA confirmed the payments were correct. However two weeks later a review of my case was made in which i then was assessed as having to pay an extra £50 A month instead making my payments £170 Pm. I have two other children living with me with my partner who currently works part time.

I have a mortgage etc and am finding the new payments hard. i was told that this review of payments would last 12 months and i was given a payment schedule for 12 calender months and was promised it would not change in these 12 months.

I have now just recieved a letter from the CSA stating that my case has been linked to the new scheme as my ex partner is claiming for a second child to another NRP which has nothing to do with me at all.

My payments now have gone up another £40 a month, as housing costs and protective earnings do not exist on this scheme. On top of which they are back dating the payments from august 09 landing me in arrears of £300 even though i just had a review in September/ october 09. How can they back date the payments when i was reviewed so recently and certainly after August 09 and nothing was even mentioned of me having to go on to the new scheme.

I am in grave danger of losing my house and making my other children homeless, i may as well give up work and live on benefits.