Bad service after loyalty

In August 2024 after wanting to purchase on my account I was advised that my account had been closed since December 2020 and I had a credit of R193.57 . I then wanted to open a new account was declined as my old one still showed and I was to request a refund which I did. Ackermans collections requested my ID and bank details and proof of name change as I've been married since my last purchase.I send the details and now they insist that I sent proof of payment for a credit owed to me , which I find ridiculous as they told me I was in credit, I just wanted to purchase on my account, why do I have to proof payment when they can see my account is in credit. please advise why this is proving to be such a difficult task I have to ask my bank for a proof of payment that dates back 5 years ago and yet they see the account is in credit .I overpaid as I paid them and a third party paid as well , so I just wanted to clear my balance at the time .I been a long good standing customer with Ackermans for years and this is how they show loyalty to customers . Unbelievable. My account had been up to date and they never even had the decency to notify me of the cancellation of my account when I had a credit balance .I always had a good relationship with Ackermans and they just ill treat me for no reason