195. If the consumer cancels the contract after the merchant has begun the performance of his principal obligation, the only sums that the merchant may exact from him are:(a) the price of the services rendered, computed on the basis of the hourly, daily or weekly rates stipulated in the contract, and
(b) as a penalty, the lesser of the following sums: $50 and a sum representing not more than 10% of the price of the services that were not rendered.