Lying ex using son as a way to get more money out of me!

I had a fling with a girl when I was 22 ( i.e 2002 ) and from this we had a son. She went against her mums wishes to get rid of the child thus she kept it. He will be 15 in January 2018. When he was very young me and his mother used to argue a lot as she would persist in using him as a weapon only allowing me to have access whenever it suited her.

I pursued with Lawyers over a number of years however that never really resolved the issue. On 1 occasion myself and his mother had a huge fallout which resulted in me being arrested for a minor assault charge. I’ve since found out within the last year his mother had planned the arrest and lied about it so I could not have further access and not be part of his life.

There was also a period of about 18 months way back through 2010 – 2011 where we agreed I would give her cash every month for my son. Approximately £150 per month. I did not think at the time to do a bank transfer for records. This was also at a time when my Ex would allow access. Over the years I have paid CSA however there has been some occasions I have refused to pay CSA as I felt it wasn’t fair as I was not seeing him.

It has since turned out that she reported me to the CSA stating I had not paid her over the period between 2010 – 2011. This has resulted recently in myself since July 2017 having to pay back backdated funds up to £450 per month presumably to cover costs of the already mentioned period. So in this instance I have been charged double the amount for a 15 year old child I have seen on and off for about 7 – 8 years of his life.