ABSOLUTELY UNPROFESSIONAL!!!!!

I keep getting an SMS stating that I owe this unknown company R9841 when I don't even have any debts or accounts. Secondly, this company wants me to make payment on WhatsApp, which is very unprofessional. Thirdly, the person's name is Nimble. I would like a formal letter of apology with the company's letterhead sent to me by no later than tomorrow (sent on ***), or else I will be writing a formal complaints letter to the Ombudsman. As a company, you should always make sure that you proof read your sms/communications before sending it out, because it is unprofessional for you to be sending other client's personal details to the public. How are you enforcing confidentiality? This company is very unprofessional, it makes me wonder how do they conduct business fairly...