Defective product repaid and new purchase

No luck, I stumbled upon a defective product. The only sound came from the right channel, nothing from the left channel. So I tried with various storage cards (SD, Miro SD, USB), same result. I then tried in another vehicle and another car radio, same result. I deduced that the product was defective and have therefore asked the exchange, unfortunately not possible for this product, only refund. Do sudden I hesitate to buy another ...
However, the only channel that worked, the sound actually seemed good, slightly weaker than FM radio.
I put 3 stars for my mixed feelings: in fact, I was fully refunded by Amazon, while I would have preferred an exchange with a product that works
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The sequel
After some hesitation due to my previous experience, I decided to buy a new product (used, for once).
Result: it works fine so I can share my experience after a few days of operation:
- Its very good, probably one of the best for this kind of device, with excellent stereo imaging, the sound just a little lower than normal, but still significantly better than the others I've tried before
- Tiny and unreadable screen from the driver's seat (1cm x 2cm)
- The steering wheel is unusable, it does not work when attached at the wheel: design flaw because the infrared diodes can not be in the direction of the camera in this case
- The cigarette lighter fleet a bit in its housing
- No fast forward, but I think it is not possible for this type of device
- Finally, small inconvenience, the device works only with the contact operated vehicle since cigarette lighter depends on it, so we can not in principle be used to stop the vehicle
I have tried that mp3 music playback, not for phone
In summary: I chose this unit to its excellent audio quality, which is rare in this class of devices, the rest can do better