Unprofessional service from owner

On the 22 3 2019 I went into Cartridges for u to purchase a portable mini Fan I charged it for a while tried to switch it on it did not want to work I took it back yes they said its faulty , unfortunately I did not have my credit card they said they needed to credit my card which is fair enough i went back with my card the lady at the desk ask the assistant to try another usb plug she said its working and refused to refund , fine she did not try to seei f it works once its charged sorry its working no refund totally and utterly unacceptable .here i sit with a broken mini fan and no refund