empty promises

So i bought a storage box at one of the PEP store in Johannesburg CBD on the 3rd of march 2020 . When i got home i realized its not as big as i thought it will be so i went to the PEP home in Eyethu mall Orange farm for an exchange they did not have it as well, When i asked for a refund cause it's still sealed and i have the receipt the lady told me that they not allowed to do the refunds cause their manager doesn't want to. She told me i can't even take something less it should be something of the same value cause if i take less its like shes doing *****. Now i don't know what to do with this box cause my things don't fit and i know that as a customer i should be able to practice my rights. and she also said that the other reason she won't do exchange is because i didn't buy it at their store so that means i should wait till i have money to travel to Johannesburg for an exchange how inconvenient is that for such a big company. If i knew that you can only return where you bought the goods and PEP managers get to decide what they want and don't want i was never gonna buy there and this was the last time.