Western Bank Ltd v Pretorius

Western Bank Ltd v Pretorius is an important case in South African law, particularly in the area of civil procedure.
Facts
The plaintiff claimed provisional sentence against the defendant on a covering mortgage bond. In terms of the bond, the defendant held himself "bound unto (plaintiff) in the sum of R160 000 as a continuing security up to but not exceeding the principal sum in respect of [...] monies lent and advanced and/or to be lent and advanced."
At the time of the execution of the bond, no money had been lent to the defendant. Clause 18 of the bond provided that, should the defendant "fail to make payment of any monies payable" to the plaintiff, then "all capital and interest" would immediately be due and payable.
In terms of clause 21 of the bond, "a certificate signed by the [...] authorised officer [...] of the [plaintiff] specifying the amount owing by the [defendant] to the [plaintiff] and further stating that such amount...