INVERTER - GENTECH INDUSTRIES/LEROY MERLIN

We purchased an inverter last year November 2022 with 1 year guarantee. After 8 months the inverter stopped working. We took it back to the store and they sent it to the manufacturer (Gentech Industries) who said that the batteries on the inverter does not carry the guarantee of a year but only 3 months. Gentech said that the inverter should not be used during Stage3-Stage 6 load shedding but only in emergencies. My question is then why purchase an inverter. The sales person at Leroy Merlin never told us this because we would have may a decision whether we wanted to purchase or not. Today (Tuesday 01/08/2023) is three weeks that this is going backwards and forwards and have still no answers for the manufacturer or the seller. I'm at my wits end and don't know what to do anymore