Good day.

Sorry for the long winded answer, but it basically boils down to the fact that they probably cannot claim this amount any longer due to prescription

Section 10 of the Prescription Act reads as follows:

10. Extinction of debts by prescription.—(1) Subject to the provisions of this Chapter and of Chapter IV, a debt shall be extinguished by prescription after the lapse of the period which in terms of the relevant law applies in respect of the prescription of such debt.
(2) By the prescription of a principal debt a subsidiary debt which arose from such principal debt shall also be extinguished by prescription.
(3) Notwithstanding the provisions of subsections (1) and (2), payment by the debtor of a debt after it has been extinguished by prescription in terms of either of the said subsections, shall be regarded as payment of a debt.

This basically means that you cannot claim a debt once it becomes prescribed.

Section 11 of the Prescription Act states which periods is applicable.

11. Periods of prescription of debts.—The periods of prescription of debts shall be the following:
(a) thirty years in respect of—
(i) any debt secured by mortgage bond;
(ii) any judgment debt;
(iii) any debt in respect of any taxation imposed or levied by or under any law;
(iv) any debt owed to the State in respect of any share of the profits, royalties or any similar consideration payable in respect of the right to mine minerals or other substances;
(b) fifteen years in respect of any debt owed to the State and arising out of an advance or loan of money or a sale or lease of land by the State to the debtor, unless a longer period applies in respect of the debt in question in terms of paragraph (a);
(c) six years in respect of a debt arising from a bill of exchange or other negotiable instrument or from a notarial contract, unless a longer period applies in respect of the debt in question in terms of paragraph (a) or (b);
(d) save where an Act of Parliament provides otherwise, three years in respect of any other debt.

So, for most debt the period is three years from the date that the debt became due and payable. In other words, three years from the date that you were supposed to have paid.

Section 13 state that prescription (the three year period) will not run under the following circumstances:

13. Completion of prescription delayed in certain circumstances.—(1) If—
(a) the creditor is a minor or is insane or is a person under curatorship or is prevented by superior force including any law or any order of court from interrupting the running of prescription as contemplated in section 15 (1); or
(b) the debtor is outside the Republic; or
(c) the creditor and debtor are married to each other; or
(d) the creditor and debtor are partners and the debt is a debt which arose out of the partnership relationship; or
(e) the creditor is a juristic person and the debtor is a member of the governing body of such juristic person; or
( f ) the debt is the object of a dispute subjected to arbitration; or
(g) the debt is the object of a claim filed against the estate of a debtor who is deceased or against the insolvent estate of the debtor or against a company in liquidation or against an applicant under the Agricultural Credit Act, 1966 (Act No. 28 of 1966); or
(h) the creditor or the debtor is deceased and an executor of the estate in question has not yet been appointed; and
(i) the relevant period of prescription would, but for the provisions of this subsection, be completed before or on, or within one year after, the day on which the relevant impediment referred to in paragraph (a), (b), (c),(d), (e), ( f ), (g) or (h) has ceased to exist,
the period of prescription shall not be completed before a year has elapsed after the day referred to in paragraph (i).
(2) A debt which arises from a contract and which would, but for the provisions of this subsection, become prescribed before a reciprocal debt which arises from the same contract becomes prescribed, shall not become prescribed before the reciprocal debt becomes prescribed.

Section 14 of the Prescription Act says that Prescription is stopped in the following circumstances:

14. Interruption of prescription by acknowledgment of liability.—(1) The running of prescription shall be interrupted by an express or tacit acknowledgment of liability by the debtor.
(2) If the running of prescription is interrupted as contemplated in subsection (1), prescription shall commence to run afresh from the day on which the interruption takes place or, if at the time of the interruption or at any time thereafter the parties postpone the due date of the debt, from the date upon which the debt again becomes due.

In other words, if you sign an acknowledgment of debt or the Plaintiff had obtained civil judgment against you within that three year period, prescription does not apply.

What you can do now, since prescription applies, is inform the creditor that the debt has prescribed. Inform them that you do not intend to sign anything or pay anything. Inform them that if they issue summons, they must do so at your current address and you will defend the summons based on prescription and ask for legal costs against them. Also inform them that listing prescribed debt on a credit bureau is specifically prohibited by the regulations to the National Credit Act and any attempt to list you will result in a defamation of character claim against them.