Your question is unclear. Is the garnishment by your former wife against you? Or is the garnishment against you by a creditor of yours that your wife agreed to pay? And what lawyer is saying that the agreement doesn't mean anything to them?
Parties frequently think that when they are personally responsible for a debt that arose during their marriage (such as a credit card or other debt listed in that person's name) an agreement by a spouse in a divorce relieves responsibility. It absolutely does not. Neither the parties to a divorce nor the court that divorces the court has the power to alter any rights that a third party may have against one of those spouses. So, for example, if a credit card balance is held in husband's name, but the wife agrees (or is ordered) to pay that debt in a divorce resolution, that agreement does NOT relieve the husband of liability to the credit card company. It only means that the wife has agreed to pay the debt. If the wife does not pay the debt in that situation, then the creditor still has a primary right to collect against the responsible party (husband). The husband may have a right to collect back against the wife, but that right depends on the wording of the "settlement" and the court order approving it.
You should immediately contact a qualified family lawyer who can advise you of your rights and possible remedies.
This response does not constitute legal advice and does not create an attorney-client relationship. I am licensed to practice only in Kansas. Seek legal advice from an attorney in your state or the state in which your legal claim exists.
The normal procedure is to return to divorce court & ask the judge to enforce the order that your ex-wife pay this debt. We call it "reducing to judgment" which basically means that you can apply for a court order to garnish her wages in order to reimburse her.
Hope this perspective helps!
A weekly guide with tips and legal advice for each stage of the process.