Very bad customer service

On 2020/03/23 my husband bought a 2nd hand mobile router. The sales person informed him that he had 48 hours to return the item should there be any problems. The same afternoon when we got home we plugged the router in to charge it, the next morning 2020/03/24 we switched the router on and tried to connect our devices, the router was encrypted and required a password. My husband then took the router back to Cash crusaders for a refund as only the previous owner would have the password.... The lady at the counter asked him a bunch of questions about resetting the device, and apparently one of the numbers on the back of the device is the "override" number???? She also informed him that he would not be able to get a refund, rather he must buy something else in the store. Our complaint is that we need a mobile router, if the supplier cannot supply one which is in good working order, why must we waste our money purchasing something else in this store???. Then we have to fork out more money at another store to buy one that works.... Further to this, I contacted the head office to lodge the complaint, without giving me a chance to state my complaint, the lady asks me for my details so she can pass it on to someone else who is going to call me back to take my complaint. I am still waiting on a telephone call, in the meantime, the 48 hours to return a good/s policy is running out