Good idea but poorly designed product

For my part, I own a vehicle with an integrated radio and there is a cassette player / CD but no usb socket ...
So the idea to read my mp3 on the car radio I liked.
The product is well packed and sent promptly.
By cons, disappointment use.
Indeed, already, I did not manage to remove the SD adapter microSD card that was inside the delivery. I thought I could put an SD card to me but suddenly I had to fall back on as a microSD or the original adapter card is blocked, or it can not be removed but it is not explained in record so I did not risk too forced to break everything.
Then, there is a mini USB port and I still thought once able to connect a hard drive over and put the device in the radio but that is impossible because the design is that cable can not connect it when the device is in the car stereo ... further disappointment.
Finally, playing MP3's complicated. I do not feel that we can create directories and navigate in it ... so all at the root of the map and continues playing songs.

In short, the initial idea of ​​this product is great but the realization is much less.
But this needs to be improved to make the most.