Have you seen your MP about it? If you have paid what you should in maintenance then they shouldn't be claiming it off you again.
The CSA get away with it by saying "you didnt inform us at the time" therefore it cannot be counted.......Bekieve me i have traced every route i know or have been told about, and as THOUSANDS of other men in my predicament will say "fighting the CSA is like a small child taking on mike tyson! i only have 3 options left, Bancrupcy (if it actually helps), Not work anymore (which i love my job and so enjoy my career), or disapear off the face of the earth and bum about. 11 years these people have hounded me like a dog with a bone, and like i said i have tried everything. I am not saying that the CSA have not done some good things, but my situation prooves why HUNDREDS of suicides and job losses have occured through their ignorance to circumstance.
I wouldn't cut your nose off to spite your face re giving up your job. Bankruptcy would help you get rid of other debt but you may not find yourself that much better off for three years.