What device, just a name will do. Much like the HyperSpin set-ups that cause no end of aggrevations and its really just shovelware with no thought. It annoys the hell out of the HyperSpin guys as their software is also basically FREE
Is it wireless or wired connected. If its an add-on thats not working on KODI, add-ons come and go. Especially 'unofficial' add-ons that get taken down through the authors get threatened with legal action for streaming content they shouldn't be
Personally though, if your having problems and the 'customer support' is useless then you would be better off starting again and install from scratch as suggested as aftermarket support by these 'sellers' is patchy if any
Get another SD card,or even better an 4GB SD card and an external USB powered hard drive, NOT one with an external power supply (well you can but its just more space). The portable USB gard drives are very very small, about the size of a small mobile phone and will easily power off the PI you bought
You can then keep your original SD card and install OSMC (basically a complete KODI 17 install that works straight after installation) then install RetroSMC which will then add a full genuine install of RetroPie to your KODI set-up, its what I use as I wanted KODI and RetroPie and stumbled across the RetroSMC installer. Problem is then you will need to configure everything. It takes time BUT you WILL have a better understanding of how RetroPie and a PI works and the knowledge of KODI that works
Its a slog at times, but you'll find people will be MUCH more helpful as its then genuine, not somebody selling something that is available for NOTHING, just your time
Have a read through these, if you feel you're upto doing it yourself
https://osmc.tv/about/
http://averagemaker.com/2015/10/install-osmc-on-a-usb-stick.html
https://github.com/mcobit/retrosmc
By a slog, you'll need to install extra software, then get to understand how to directly access the PI through things like command windows and start to grasp how Linux works