summons by orthodontist

ILLINOIS.. daughter went to orthodontist for nearly a year. Insurance expired and discussed with ortho office, found account balance at zero and said would contact them to continue treatment if/when new insurance or could afford. Now a year later have received a summons for $600. Contacted atty office three times and they say unable to obtain a billing history. Court date is next week. Am trying to work with them, am certain this is a mistake, but can't afford an atty and they seem to be giving me the run around on getting info. Dr's office won't talk to me, says it was turned over to collections.

Any ideas or suggestions? Think I have the $63 arranged to borrow to go to court next week, but have nothing but my notes on the phone calls to refer to and an old statement from the Dr's office showing where I paid $750 and the insurance was billed.