Has anyone been successful in the magistrates courts?

My situation is this, I Split from my ex wife in 1998.

I paid CSA from day 1 and being in the Army they had me by the short and curly’s.

In June 2011 i stopped paying for my eldest son after he joined the Army as well, the CSA sent a Deductions from Earnings Order to the Army pay HQ in Glasgow to reduce my payments from £402 to £261. I have payslips and the Paperwork to prove it.

Well that was until last week when i had a call from them saying i had Arrears amounting to £11300 and that a new Deductions Order for £722 will start straight away. The monthly figure was worked as £572 for what i should have been paying and then £150 to pay the so called arrears.

I have had an appointment with the Citizens Advice Bureau, we are going to write a letter of Appeal for this amount.
On returning home, i had two letters from them with a breakdown of payments etc.

I don’t really speak to my son these days as his mother has brainwashed him against me, but i am sure he works more than 24 Hours a week, how can i get proof about this? As i know he won’t tell me himself and his workplace won’t as well.

What i can’t understand is why in June 2011 was it ok for me to pay £261 then all of a sudden in December 2013 i now have arrears and have to pay £722? I have never missed a payment as it has always come from my wages.

I do have a small light at the end of the tunnel as they said i only have to pay for him until Sept 2014, but will have to carry on paying the arrears.

I also pay DD £215 for my daughter directly to her mother as we both don’t want anything to do with the CSA, I have explained this to them but they are not bothered.

I want to appeal to the magistrates courts about this, has anyone had any success with going down this route?