The first question is whether you had something in writing regarding this payment plan with the debt collector. If so, the terms of this writing should govern your arrangement with the debt collector. If you were late with a payment in December 2013, that may have been a breach of this agreement. As a result, there is no reason the debt collector could not go to state court to sue on the remaining amount of this debt. It is unlikely that the debt collector has "waived" the right to pursue a judgment in court. You should seek the advice of local Lakewood counsel to file an answer to the complaint filed against you in court. You may be directed to engage in mediation, and you may be able to get a payment arrangement back in place. Again, consult an attorney asap.
Disclaimer - this answer is for informational purposes only and not for the purpose of providing legal advice. You should contact your attorney to obtain advice with respect to any particular issue or problem. This answer does not create an attorney-client relationship. As of now you have not retained this attorney or this firm to represent you in any matter. To the extent there are any issues for which the statute of limitation has or will run or interests which are being impaired, immediately contact counsel to assist you. The opinions expressed are the opinions of the individual author and do not reflect the opinions of any firm or any individual attorney.
Acceptance of partial payment does not invalidate the claim. If you still owe a balance, then they can pursue collection. The debt collector may have been running up against the statute of limitations for the claim, which might be why they filed. If you can work out an agreement for a payment plan and the dismissal of the lawsuit, that might be best for you. If you can't work anything out and you are required to appear in small claims court, make sure that you bring all of proof that you have as to payments made to offset the amount claimed.
Legal disclaimer: The answer provided: A) is for informational purposes only, B) is not intended to constitute legal advice, C) should not be relied upon in lieu of consultation with an attorney, and, D) does not establish an attorney client relationship. The answer may be different if all of the facts were known.
If you have not paid off the claim, you are still on the hook for the balance and the lawsuit is good. Generally, the debt was due some time previous to your making payment arrangements, so your payments, while being credited to your balance outstanding, do not make some legally binding agreement to not sue you. Creditors sue you so that they can garnish your bank accounts and your wages (at 25% of your pay per pay period). If the debt is large, filing Chapter 7 makes a lot of sense. But as a small claim, the debt is probably not that large, and filing a bankruptcy may not make any sense. However, most people I have met with debt problems have a lot of other unpaid debts. It is better to look at your entire indebtedness and figure out how to put it all behind you so that you can move forward with your financial life without fear of collections and lawsuits.