Windows 10 Not Activated ( running on trial version )

I bought a laptop from cash cruisaders in Silverton wich was displayed with windows 10. I looked on the computer and it displayed under properties that windows 10 is activated. Price was R5000. (Old machine but I 7 , 500 harddrive etc ). After three weeks said windows Not Activated. Took it back and they activated it. After 3 months,Not Activated !! Took it back and they said I must pay R200 to activate it again and it is actually a trial vertion of windows 10 and only lasts 3 months!! Now after paying R5000 for an old machine I must pay I don't know how much for windows 10 to have a legit windows 10 on my laptop. So what did I actually buy if I didn't get windows with, and it was displayed as with windows 10 on it!! I urge other people who buy computers from these people: check the windows on the machine you buy, because it is a sales trick to put trial vertion of windows 10 on the machines and after a week or two: NO WINDOWS . ( Not Activated )