Legality of being sued for services without a contract?

If money has changed hands, a contract has been created although not written. Small Claims courts generally require payment for a service that has been completed, even if the amount is greater than expected. Conversely, if a payment has been made for a service not completed, a refund of the payment is likely to be required. Services complete as to functionality will likely require payment even if ancilliary damage is done during the course of the service.