hey,
i had the same problem and so was the case with my father's & mother's iphone 5s
when i recieved the clio 3 weeks ago at the dealer the agent from renult said that thier is a problem with the 5s and the medianav bluetooth - device appears on list but doesn't connect or connect and then doesn't work with the medianav...
at first, after a few attemps - both my parant's iphones did work but mine still didn't connect proparly although i tried again and again
after the device shows up in the device list i tried to connect, it said "key 0000" (default key) and after a few seconds, while waiting for the iphone to ask for the key, the medianav said "wrong key" and that's regardless to the fact that i wasn't promped with the key on my iphone
i tried to change the key - same thing
at last - i deleted all the bluetooth devices saved on my iphone one by one manually and then medianav showed up and asked me for the key and connected. if i remember right, I shut down contacts sync (inside the device in the iphone bluetooth list) and only after that it connected
hope it will help who needs it
🙂