This is all about protecting yourself when your exspouse has clearly failed to do what the divorce decree required him or her to do. It’s the procedure I suggest you follow when you need to (a) make it clear to your exspouse that he or she is not complying with the decree and (b) put yourself in the strongest position possible to get compensated for the cost of using the court, if that becomes necessary.
Write your exspouse a letter. In that letter you need to do the following:
Use correct spelling and grammar. A judge may be reading this later.
State in simple, matter-of-fact language what the decree requires, referencing section or paragraph numbers where appropriate.
State in simple, matter-of-fact language what you can observe about your exspouse’s lack of compliance. That is, if all you know about the payment on the car is from the online site you consulted, don’t say “You haven’t paid the car payment in three months, probably because of that bimbo you’re boinking.” Instead, say simply, “the record I checked on August 17 at [the web site] indicates no payments for June, July, or August.”
If your exspouse’s lack of compliance is damaging you, describe the specifics.
Give your exspouse a reasonable time to comply, a date that really is attainable.
Avoid any assumptions about your exspouse’s motives. Leave that to the court.
Send the letter by certified mail. Then, if the reasonable time expires and your exspouse hasn’t complied, you’re relatively well positioned to ask the court to grant you the relief you need (to the extent your exspouse can comply), and you’re also well positioned to ask the court to find your exspouse in contempt of court and to order your exspouse to pay you the attorney’s fee you have incurred to enforce the decree.