Facts
Fritz and Renate S. are tenants of an apartment in Winterthur. The landlord, Helena M., notified them of a rent increase, which the tenants contested before the Conciliation Authority for Tenancy Matters of the District of Winterthur. At the hearing on March 19, 1991, the tenants accepted a rent increase of CHF 47 per month, but the parties did not reach an agreement on the costs and compensation consequences of the proceedings. The Conciliation Authority determined that no agreement could be reached and dismissed the tenants' request that Helena M. be ordered to pay an appropriate litigation compensation due to vexatious litigation.
Helena M. subsequently did not appeal to the Rental Court, so the rent increase did not become effective. In response, Fritz and Renate S. appealed to the Rental Court of the District of Winterthur, requesting that the costs of the conciliation proceedings be imposed on the defendant and that she be ordered to pay the plaintiffs appropriate litigation compensation. The Rental Court treated the submission as an appeal for nullity and, by decision of June 7, 1991, did not enter into it due to non-compliance with the ten-day appeal deadline.
On the appeal for nullity filed by Fritz and Renate S. against this decision, the High Court of the Canton of Zurich again did not enter into it on July 19, 1991, because an appeal for nullity against the decision of a court of cassation was no longer possible at the…