still owed child maintenance arrears 20 years on

Hi,

Long story short, my daughter is now 29 and I am still outstanding over 10K of child maintenance arrears from when she was 2 to 18 (confirmed by the new agency when they inherited the case). CSA were involved right through and its been to ICE who found in my favour. The new agency (I have no idea what they are called now) have my case and ex has been paying arrears for god knows how many years at £20 a month, however he is now 60, and by my calculation will be dead before he repays everything he owes. I dont know the reason why the CSA and now the new agency are allowing repayment at £20 a month (I suspect he was/is in receipt of some kind of disability allowance that permits this).

Is there anything I can do to get this repaid or am I stuck with this? I did message the ex via facebook and said I would accept half the money in a one off payment and close the debt but he didn't respond.?

Thanks