Inverter

So here's the thing, 22nd of April this year we bought a inverter which included the battery box on wheels , it needs to cope with , 2 laptops, 1 printer ( not used consistently) , Wi-Fi and the home alarm system ( we work from home). If we get load shedding in the evenings the laptops are closed and we use the TV. So this system has failed, I took it back 2 weeks ago and there's no warranty left on the battery's only the inverter is still under warranty but thats not the problem apparently. It cost us a lot of money and it hurts when we can't do our work, so please let me know where we stand on this matter, we don't have the money for another one Thank you Mike Imrie ***