Spar Century City - shocking customer service

I tried to return a cell charger to the store on the 19/4 The charger was bought on the 8/4. I explained to the store manager that I hadn't had a chance to bring it back sooner. But that it wasn't needed because I had found my old charger. He said the reason he cannot accept the return with the relevant purchase slip. Is because even though there is nothing wrong with the item being returned he doesn't know if I used it. So they won't accept it. He also doesn't seem to know the difference between 11 days and a Month. Saying I've used it for a month. Saying to me that spar doesn't do rentals. Complete disrespect basically accusing me of lying. This store was conveniently close to where I stay, but I think I'd rather spend my money elsewhere.