If they are garnishing your wages, they have a judgment. The first thing to do is to review the court file of the case in which the judgment was granted. There may be a basis to challenge the judgment (have it set aside). For example, if the service was legally defective under your state's law, that may be grounds to set aside what I presume to be a default judgment.
After review that from a procedural standpoint, consider the merits of the case. Do you owe the money? If not, get ready to try to fight. If so, you may be better off to try to cut as favorable a deal as possible. That is where contacting the other side's lawyer will come in. You do not have a lot of leverage (unless you have good grounds to have the judgment set aside and make the creditor start over). You may, however, be able to offer a lump sum of money right away as payment in full of the debt rather than relatively small garnished payments from your paycheck every few weeks. If necessary, you may be able to borrow money from another source in order to be able to make a lump sum offer of, say, 60% of the original principal balance, payable within ten days, if the creditor agrees to set aside the judgment, accept the payment as payment in full, and report the account as paid in full to the credit reporting agencies.
Finally, if you situation is dire enough, you may need to consider a bankruptcy filing. Many bankruptcy lawyers offer free initial consultations if you believe that might be the answer (considering your overall financial situation).
I am not admitted to practice in Oregon and my comments here are for discussion purposes only. Rely on experienced Oregon counsel for precise answers to your questions.