Miss a payment, was threatened, embarrassed and harrassed

I have purchased a fridge on credit at Home Corp and missed one payment which was my first payment due to my card being lost and account blocked. A week later they called me and told me that the payment did not go through. I told them that I will come to the store on weekend to pay, they kept on calling during the week and I told them the same thing, until today (Friday 02.02.2018) that they have sent a guy to my work place to threaten, harass and embarrass me. The guy told me that I have a bad attitude and he can do whatever he likes to me as I am owing their store an installment. I told they guy that what he was doing was against the law but he told me he can do whatever he like. I am very disappointed with Home corp's conduct of business. If they threaten their customers for payments like some township mashonisa (loan shark). I'm lost for words for the lack of their professionalism. I will definitely take this further as I believe no matter how much a customer owes you, you don't send some "Goon" to threaten them at their workplace.