Can MP help with CSA?

My partner has a child from previous relationship, ex has never asked for financial support even though it had been offered on numerous occaisions. Ex has full support of my partners family as they live nearby. Last Feb partner got a call from CSA regarding maintenaince and it was taken straight from his salary. This was the first claim in 8 years. I wasn't very happy as I was 5 months pregnant at the time. Anyway at the moment my partner and I are struggling to meet everyday living costs. I work part time and pay for childcare and it upsets me that part of our household income is supporting someone who has never worked and never intends to. I feel that my partner, myself and our daughter are having to make sacrifices for the ex and I think it's very unfair that one person can just sit on their backside while we have to go to work to support her to do this. We are in financial strife and our disposable income is what I bring in �500 a month. Can anyone help?