How can you be taken to court on a medical bill when you made payments every month?

I have a medical bill in which I owe $900 and made every attempt to resolve the matter offering $100 a month payment and they turned me down. They want the total amount and I have till the court date to pay it in full. They will not take payments now. Anyone have any suggestions or had the same issue they told me will put a 20 yr lean on my property.