i think you're going to have a hard time getting them to vacate the judgment. you have no meritorious defense as to having the judgment vacated, and they have no motivation to do it themselves. collections firm typically will not vacate a judgment for a payment, and why would they? they went through the trouble of obtaining a judgment, and vacating it will do absolutely NOTHING for them, even if its paid by then.
which isnt to say it doesnt happen, just very unlikely.