Charging a bolt for R250 .*******!!!

On 13/07/2021 I took my car's starter to the business to be repaired, they repaired and I fitted it on my car.on 14/07/2021 I got it from the repair shop and it failed. On 15/07/2021 the next day I sent the starter back and they requested for the car to come to their work shop to check it. They worked on my car without my approval and they called me when they were 30 min to close for the day to go fetch my car, billed me R250 for a bolt that was there initially. They claim that the bolt was not there .they ripping people off. How can one bolt be R250. Their customer service is bad and they don't communicate with the customer before they do work on the car.