Internal storage not enough

I have Supersonic Matrix SC-999 tablet. I think there is something with internal memory. I can't add apps because the internal storage total space shows 0.99GB and available space of 95.52 MG. The only app in it is Google play services and Google play store. I use to have Facebook in it and but I have to move it to SD.

The unit on the back says it has 8GB. Is there something wrong with unit? When I first got it I was able to install lots of Apps including games and XMBC. Now I get memory error when I try to install app. How I fre up internal memory?