Intercepted State Tax Return Went To Child Support

Child Support services intercepted my State Tax Return. I immediately called and was told that they had to hold it for 45 days. After a couple of months I still had not received it...went online and saw that they had credited it to my ex wife. After numerous phone calls the caseworker called me back and told me that someone in her office had taken the check off hold by mistake. She said they use two sets of books and that one book said I owed and the other said I owed nothing. They told me they were sorry they made a mistake but there was nothing they could do. They have asked my ex wife to pay it back because she had received it in error (after no child support for at least a year) but also told her they had no legal grounds to pursue it. She offered to send them a money order every month until it was paid and I haven't received anything. Per our conversation I am not the only one that this has happened to at that particular office. I feel if their office made the error then they should correct it.