Bad Treatment by the Manager and his employees

I bought a product at Hifi Corp and it was a wrong product. I called the Head office of hifi and was advised to take it to the nearest Incredible connections for a refund. I went to the Grove Mall and the manager there wanted to rob me to say that he is gonna deduct 15% from the refund I asked how so, he said cos I opened the box of the item which is a book cover. The box was neatly opened and I asked him how was I wupposed to see whats in the box if i dont open it. It was then my word against his until two of his employees tried to calm.the situation. They then asked me to fill in refund forms and that it will take 21 days for a refund. I told them there is no way a refund can take 21working days. I called in at Hifi Corp to find out and was advised that refund takes 7-14 days so the Manager and his staff are ****s who manipulate customers. I called in today the 10th for a follow up of my refund as no communication was received with any reference number. The store Manager told me today (10.10.2025)that the forms have been sent to head office and to my surprise the head office didnt receive anything from the store. The store manager and his employees are spiting me and this is a serious offence to me as I am waiting for my refund and on top of it, I am the one who has to make follow ups. I have never felt so small and hurt as a customer. This store they have given me the worst experience ever. Thanks to the lady at the hifi head office who was honest that no forms were received and has opened a complaint ticket for me.