BMW Midrand stole my vehicle parts

I took my 3 series to BMW Midrand for SOS issue and the couldn't repair the issue because the say the warranty will not be covering the repair due to the modification that was done on the roof. Which was done by the previous owner, and had only been driving the car for a month when the issue occured, and they did inspected the car and said it fine before I purchase it from another dealership. Now I just discovered that they took out the Bluetooth and Audio module because they said it's faulty and never put it back as I could afford the repair at that time. Why are they taking my old parts if they don't cover the new, and I asked the to reinstall everything the why it was and they are ignoring. I have sent Beverly an email in May and she never replied.