There already is a very long thread with good tips to improve your credit score
here.
Like suggested, a credit card is the easiest way to improve your rating. And remember, the used:availale ratio is very important. Get a high credit limit but only use a little bit. Protect yourself against fraud by setting your daily limit to a small amount. Pay it off ASAP!
Something simple like a cellphone contract might also help. But don't incur extra costs, just to get a good score.
If you pay for a Telkom line, make sure it's in your name.
Not all insurers report your payment profile to credit bureaus. Or your insurance might report to a different bureau (there are 4).
Like mentioned, affordability is also a major factor.
If you have judgement or late payments against your name, the weight it carries reduce each year. So you might just have to give it some time.
PS careful with those payday loans. If I was a company where you applied for a loan or credit, and I see payday loans on your statements, I'll be weary because it brings your affordability into question.
I see you said you need a home and car loan. Are both really necessary now? Remember that a good deposit be a bigger contributing factor than a credit score towards a good interest rate.
Hope that helps.
EDIT: With which bureau? Some score out of 850, others out of 1,000.