Finance declined after a pre approval was done

Hi,<br> <br> I app**** for Finance through Wesbank.<br> A pre approval was done and i approved subject to verification.<br> <br> After all documentation was completed and sent then i was declined due to credit score.<br> Note i have 0 debt on my name with an income of +- R16000.00 <br> <br> What is the qualifying criteria then if a person with no debt and an income of R16000.00 per month wont qualify.<br> Also what is the use of being pre approved if it still gets declined.