If you pay for something, you are entitled to get a useful value for your money. There is no warranty on used goods unless the seller gives you one. If you promised a payment on the first, it is late on the second. Repair shops are not required to give warranties. They can still be held liable for work done negligently or intentionally wrong.
Business owners have a duty to keep their business premises reasonably safe for their customers.
Every person has a duty to act with that degree of care that is exercised by ordinarily prudent persons under the same or similar circumstances. A person of sound mind is presumed to intend the natural and probable consequences of his acts. An actual mistake cannot be the basis of a contract. You cannot form one if you are mistaken about its terms. Accident means that the occurrence was not the result of intent or negligence on anyone's part.