If you owe the money you might try to figure out a way to pay it. If you had been overcharged $15,000 you would make at least 10 phone calls to try and get your money back.

It is an unfortunate mistake but you should try to work with the builder to resolve it before it gets worse.

First if all, "can they do this..." YES. Did you use an Oklahome New Home Contract, or Builder provided documents? If it was the OREC New Home Contract (04/2007), then it states all agree to handle disputes through mediation first, then legal action. Since this is not a legal forum, it will be best to contact an attorney ASAP.

It all depends upon what was in writing & what (if anything) was agreed to outisde of written documents. If you agreed to changes, then you owe, regardless of what is in writing. That's just the moral thing to do.

If you do not have these changes/agreements in writing, then it depends upon (a judge's) perception as to what, when, where, why & how. If the Builder has no copies of written & signed agreements, then he/she is wasting time &/or money.

Since the Builder has already filed, it will be best to get your own attorney & let him/her advise. Best of Luck