. At what point should mediation be explored?

Divorce granted 4/11/11. Settled out of court. Many issues remain. Agreement not being adhered to by ex-spouse. Probation payments of alimony are not being made. Direct payments are being made. Ex-spouse is not paying the mortgage(s) as agreed. I have had to pay 3 months of mortgages in 2011. Ex-spouse recently separated from long term full time employer and looking to appeal all aspects of settlement agreement. Paid off my lawyer this year. $30000