I was a trainee at shoprite waterberg region in 2016 and completed all my modules, worked as a sales manager in one their store however I was fired

I was a trainee at shoprite waterberg region in 2016 and completed all my modules, worked as a sales manager in one their store however I was fired. Thing is when I was paid my severance package, I noticed that a sum of R25 000 was deducted and was stated that it was for the studies but I was never given any certificates. Is this fare? Can they at least give me my certificates as they have deducted the monies? Please can anyone assist me with the matter please.