Sick and tired

I don't even know where to start. I have been paying my granny's account for the past 2 years. Last year May I finished the account she had at Lewis in Simonstown and she bought new stuff in Bloemhof that I said I'll pay for. First payment was due beginning June. I paid the last week in May. I have never ever been a day late. Last year they started calling to say we haven't paid and they're going to add interest etc etc. It got to the point where they went as far as to go to my granny's home. When she wasn't there they told THE NEIGHBOURS that they are going to repossess the stuff because she hasn't been paying. I submitted proof of payment for EVERY SINGLE MONTH AND it was verified by my bank. They called her daily still. Then the regional manager send us a message ON WHATSAPP to tell us to pay. I spend over R300 in airtime trying to sort things out. EVENTUALLY they told me that they made a mistake and the money went to the wrong account. How the hell that happened I neither know, nor care. I got a print out to say that all was up to date. Now they started again. During lock down the store wasn't even open. But I still pay every single month, on time. And the whole process started over again. AGAIN with them telling her that we haven't paid. Then I asked for the manager's details so that I can write a letter to them. I need that as proof before I go to the Ombudsman. She never rep****. Then I tried again. I phoned the store and ask for the details because I'm definitely taking this further. They are charging interest and we have never even been a single day late. They send a message to reply that we haven't paid but still no details for me to write the formal letter. I want to settle the entire amount on Friday but now all of a sudden I can't get hold of anyone. I am beyond angry and fed up with this bad service. P.S. They told me it's because I still used Simonstown code as reference. I read back the code I have. It's Bloemhof but "SOMEHOW" the money still went to Simonstown. According to the person I spoke to. The irony is that I have a debit order with a fixed reference number. I don't touch that account. The money just goes off. So how convenient that sometimes it goes to the right branch, and sometimes it doesn't...