Just to be clear the black dongle that came with the remote control is not a bluetooth dongle, it is an RF dongle which talks to the remote and so will not show up as a bluetooth dongle.
The WiFi dongle should work fine if you just plug it into the Slice USB ports... I assume the remote control is working correctly?
It would also be useful to check one of the other USB ports, just to check they are all working correctly (maybe just using a USB keyboard if you've got one handy)
Finally you can try plugging the WiFi dongle into a PC or Mac (or Raspberry Pi!) and check to see if it does anything, this should tell you whether the dongle has been damaged in transit...