Avoid Showmax 14 days Trials

I registered for a 14 days mobile showmax trial which I cancelled before the trial end date, I then register a new full package under my partners name. Showmax has been attempting to debit the R39 since then, and it's causing me bouncing debit order charges, I did notify them and they promised me it's been removed from the system, now I'm experiencing never rending banking charges.