It really sounds like it's time to get another opinion. Typically there are various ways to resolve "errors" or to at least minimize their effect the earlier you catch them. Ask your Broker how the mistake happened and what they intend to do to resolve it. If you don't get a satisfactory answer, take your entire contract to an attorney for review and get their opinion. These steps should happen immediately. In Real Estate, Time is of the Essence!
Without reviewing everything in detail, no one can properly advise you and you should be wary of quick and easy advice. We all make mistakes, what proves our character is how we resolve them. I hope it all comes out okay for you.
A contract isn't supposed to be a "gotcha" document, it's supposed to be a document that represents the agreement between two (or more) parties. If the document doesn't represent your agreement, tell everybody right away that there's an error and you would like it corrected ASAP.
If anybody balks, or outright refuses, then it's attorney time.
All the best,
Your broker prepared the counter offer and I will assume you read the counter document and signed it which indicates you agree with what is in the document. Your agent is "representing" you as a seller's agent in a real estate transaction You and your agent are equally accountable for the error. The buyers agent will refer to the written and signed document as credible proof of a legitimate counter offer. Please discuss with your attorney in Wisconsin---you will need to know if you have any recourse or not. Thanks and good luck!
You may very well eventually need an attorney. I'd suggest starting - quickly - with your Agent's Broker-in-Charge ... assuming there is such a person at their Brokerage Firm. Still, if you are in NC, it will be very difficult for any of us NC Realtors to provide you advice given your pre-existing relationship with another Broker.