Used car purchase Radio didn’t go when buying!

Hi, I finally bought a Mazda RX-8 today. (At dealer’s) Now, however, one thing just doesn’t leave me alone. At the rehearsal we found out that the radio etc. is concerned, but nothing is to be heard. In other words, on the display you can adjust the volume, transmitter etc., but you can’t hear anything. We bought the car anyway. In the internet offer was under equipment “Original Mazda Radio System”. When we had visited the car stood at the door dressing and “Bose Soundsystem”. We were already happy, until we just noticed that there was nothing to hear. My question now, which unfortunately came to me only later. Can that be that the Hander or the previous owners have expanded the Bose Soundsystem and now there is nothing in it? Unfortunately we did not check that. And if yes, I have a right to get at least a normal soundsystem from the dealer, although I knew at the time of the car purchase that the radio was not perfect because on the Internet it was clearly advertised with sound system. (Vehicle is not yet “transmitted” is thus still standing at the dealer) That would otherwise be deception? Do I see that right? (Can it be that it is only on a cable or the like, then the above mentioned is naturally lapsed) Ask for help. Thank you