Staff sell products not fit for purpose - with no acknowledgment of their responsibility to do so

We needed an appliance that kept our WiFi Router up during loadshedding. We were sold a R7K UPS unit - which within 3 rounds of loadshedding was unable to power the router for longer than 15 mins. We returned the unit and were told that keeping a router up for 2 hours was not what a UPS was designed to do. We had been sold the wrong product. They offered to sell us replacement batteries at a discounted rate - which doesn't really help if that is not the purpose of a UPS??? The request to replace the UPS with a product that is able to keep the router powered for 2 hours has been rejected.