Working makes you an employee — paperwork or not
Your rights flow from the fact that you work for an employer, not from a piece of paper. As soon as there's an agreement to work for pay, an employment relationship exists and the Basic Conditions of Employment Act applies in full. So 'we never signed anything' does not mean you have no rights — it means the employer skipped a step the law required of them.
What you're entitled to anyway
Without any contract you are still owed at least R30.23 for every hour worked (with a 4-hour, R120.92 minimum for any day you report), at least 3 weeks' paid annual leave a year, paid sick leave (the days you normally work in 6 weeks per 36-month cycle), and the right notice if employment ends. If you work more than 24 hours a month, you're entitled to UIF and to COIDA cover for work injuries. You're also protected against unfair dismissal — you can't simply be let go without a fair reason and process.
The contract is the employer's duty
Section 29 of the BCEA requires the employer — not you — to give you written particulars of employment: your pay, hours, leave, duties and notice. If you don't have them, that's the employer failing a legal obligation. You can ask for them in writing, and you can point to the lack of a contract as evidence of non-compliance if a dispute arises. You should not be penalised for the employer's failure to put things in writing.
Proving your terms without a contract
Without a written contract, keep your own record: the days and hours you work, what you're paid, and any deductions. Messages agreeing your pay or hours, and payslips if you get them, all help. If your rights are denied — underpayment, no leave, unfair dismissal — you can report the employer to the Department of Employment and Labour or refer a dispute to the CCMA, both free, and your records become your evidence. Compliance tool, not legal advice.