CSA calculations

hellesbelles67

Hi, my husband has been paying 400 per month for last 11 yr to his ex wife in a private agreement, he went on secondment from Jan to Oct last year to the Olympics, worked bloody hard and got some over time in, his ex wife decided that she should have some of the money and went to CSA in Oct just as he came home, so they used his wage packets from the 3 mths before he went as this would be his now regular normal wage. That was fine, although she wasn't happy as the payments changed by approx 10 per month he thought she would get the Olympic money. In Jan he got notice that he had been overpaid by £2500 gross, £973.00 Net and we are now paying 200 per month back since then. We contacted CSA and gave them and sent them all details as he was now getting less money, they calculated that we need pay only 55 per week, which we repeatedly queried and did pay the ex 100.00 per month extra as we didn't think it was right. She thought we were stashing the money away somewhere and appealed even though we repeatedly told her the reason.
My husband has now received confirmation that we need to go back to paying the original amount per week, less 3.00, even though we are 200 per month worse off! We have asked or the calculations and they are taking his Ytd figs in calculating the weekly figure even though she didn't o to them until end of Oct and not taking overpayment into consideration.
Has anyone any ideas why they are doing his?