Unfortunately, you have waited too long. You thought this thing would just go away. You should have appeared in court when they brought the judgment against you. Now you will have to pay court costs for the judgment and the garnishment. Pay what you owe them, and consider it a lesson learned.
Depending on what state you reside in, any action you took with this company before yes they can still garnishee your wages.
Normally if you have not paid on an account in 4-7 years most states will not allow them to continue to pursue you for this debt and it would normally fall off your credit report.
If you made a deal with them to pay on a payment plan, and you started this plan it is almost like starting over again. When you agreed to the pay plan it was like you were agreeing that you owed them instead of the company that you originally started with.
So if you agreed to a payment plan 2-3 years ago, and signed the agreement, there is a possibility that they can now garnishee your current wages.
I hope this has been of some benefit to you,good luck.