Bosch Service Incompetence - Misdiagnosis and High Charge for Minor Issue

The Bosch Unlimited 7 cordless vacuum cleaner keeps stopping and shutting off. I removed the accessories and dust container, but the issue persisted. I also replaced the charger, yet the problem continued. Since only the motor remained as a possible cause, I called Bosch authorized service center, thinking they would stand behind the product, especially with the 10-year motor warranty they advertise. They took the device and claimed the control board needed to be replaced, quoting a price of ₺8000. I declined the repair, but they still charged me ₺700 for the service. In reality, there’s no major fault—the vacuum just shuts off occasionally when shaken, clearly due to a loose connection. I plan to fix it myself, but I’m very dissatisfied with both Bosch and their authorized service. They not only fail to stand behind their product but also show a clear lack of competence.