Around here it is called discovery. The opposing party must provide you with evidence they will present in court so that you may have time to prepare a rebuttal. They don't have to provide copies of things you should already have, such a sales contract.
You can subpoena evidence from them. The first thing I would want is a copy of their home inspector's report to them. If he found nothing wrong with the shower, he will pretty much have to say so in court to protect his reputation.
--Andy Asberry recommends NewsGuy--