Hi - my name is XXXXX XXXXX I'm a litigation attorney. Thanks for your question. I'll be glad to assist.
You do have a right to enforce the settlement agreement as written, and if they have violated it, you can file a petition in court and ask the judge to compel the lender to comply with the terms of the order.
You should also seek an accounting from the lender because if the lender raised your payments to cover the taxes, and then recovered those funds from the tax collector, then the money you paid out in payments should be returned to you - - which should cover the current delinquency (or close to it).
This is definitely a rare and complicated situation, but you do have the right to seek relief in court and get things straight. You're going to need much more help than can be provided here. You're going to need a local attorney to assist you in getting this resolved.
However, to answer your question, you do have the right to require them to honor your agreement, to return any money you paid over in error and to seek damages for what this debacle has caused you.
Thanks for allowing me to assist, and if you have any additional questions, please don't hesitate to ask.