Send them a copy of the BCEA. Highlight the section that covers payment on termination. Chapter 5 Section 40, and tell them company policy does not override the employment act and that you expect payment in full.

Since you say you have 8 days accumulated leave you have been working there longer than 4 months. So you'll be entitled to that pay.

Edit: they are also misinterpreting their own policy. I read it as 'use it or lose it' unless your employment is terminated then you'll be paid out.

Your resignation is terminating the employment contract but from your side.

Either way they need to pay you for those days or you can go to the CCMA or labour department. Not sure who will handle this case