Image Motor Sport - Only exchange policy???

I bought a new amp for my car from Image Motor Sports in Amalinda, East London on Saturday 26/11/2022. I thought my amp was broken, so decided to buy new one. When the guy who needed to do installation arrived, he found that there was only a problem on the wiring and that my amp is still in perfect working condition and didn`t need the new one. I was just visiting my parents that weekend and don`t stay in East London. I asked my dad to please return the amp on Monday 28/11/2022 and get a refund because this amp was thousand of rands and I can`t afford to just keep it if I don`t need it. My dad went to return the amp, but they refused to refund me, they only allow exchanges. I can understand if you buy a small thing like a bulb, but surely items that is high value and wasn`t even used and returned in a day.