Poor communication and poor information recording on accounts

I have made one of my rare orders to Avon of which the last which was paid was done in December 2018, on the 15th and 16th. Every time I visit my Avon account, I am surprised to note that I have an overdue account. I placed an order on 12 February 2019, only to discover i still owe. I send an email credit control at Avon, first thing they do not fix anything and what is most irritating is they do not respond to an email query and yet their control department is not contactable via telephone, except that they were quick to ask me to pay over a R1000.00 that I supposedly owe them. I had attached proof of payment. When I called on Monday, 18 February 2019 to sort this out, I just could not understand what the customer care person was really trying to explain to me. This is truly disturbing because I do not buy on credit from Avon, and I am surprised how did I receive products if I owed them. I want them to correct their mistake and correct their records and clear my account of debt