Ackermans not keeping up to their promise of refunding my money

I mistakenly transferred funds into the Ackermans account in 2021 around March... My account was paid up and closed already so I called their financial department and was adviced to go to the nearest store and submit a letter and bank statement. I submitted the requested document, then after a month or two I went back to enquire how far my matter was, I was told they never received the documents (which was not possible as the manager of the seshego branch submitted on my behalf in the store). I then had to resubmit which we did but still to date Ackermans has not returned to me. I asked if I can take anything in the store for the same amount of cash but they said it's not possible. Please help me get money back from Ackermans.