Disgruntled customer

I bought a RCT inverter from this company and I am very disappointing that my inverter has only lasted 9 months, it only lasts 1 hour now, with nothing plugged in for that hour then I only plug my laptop in and it beeps at me to unplug it. This is unacceptable my model number is RCT-2000VAS. What can be done about this, it is not acceptable that this only lasts this long after charging all night. It should not happen for such an expensive product in such terrible load shedding times in South Africa, I can not afford to buy one each year, this should not happen.