Foshini Debt collectors harassment

We recently experience regular hang-up calls at our business and after looking up the number on True Caller found it to be Foshini Debt Collectors. I called them to report to a manager that the staff was badly trained and it is harassment calling a company every day and then hanging up when they realize the person they are looking for did not answer. When asking for a manager I was told to speak to complaints, but could not tell me how to reach them as it is not an option on the main menu. Not impressed with the training of your staff.