Unfair business practice

I pawned my Huawei Y7 2019 device at Cash crusaders Arcadia branch(Pretoria) and due date for buy back was on Friday,25 August 2023. My understanding is that the franchise does offer a grace period of 2-3days in the event that a customer is unable to present him/herself at the store on the buy back contract expiry date. Monday morning(28 August 2023),I went to the store to collect the device,unfortunately the cashier told me that the item has already been sold. I was shocked to learn that,when it was only kept for one day, which was Saturday(26th) since the store doesn't trade on Sundays,thus Sunday can't be counted. When I got home I contacted the manager who confirmed the news but he failed to give satisfactory information on why the device was released before end of business. My idea was the store "marked" the device especially its condition was new and the that model does not lose value compared to other models(it has been trading for between R3000-R3500 for the last three years),hence one would rarely complain about its performance. Technically it is a brilliant phone. On other hand on the day I pawned it,surprisingly the consultant who assisted me wiped out my Google account and asked for a charger which is uncommon in line with what other stores operate. It gave an impression that they intended selling the product. I need answers on why my device was sold during the grace period and if it was a coincidence that it was sold within minutes after it was placed on display,especially when the consultant who assisted me previously said one same model took about 90 days to be sold. I strongly believe that the store is dishonest and exercises unfair business practice.